وقتی می زنم sudo apt-get update این هارو چاب می کنه : 
Ign http://extras.ubuntu.com natty InRelease
Ign http://security.ubuntu.com natty-security InRelease             
Ign http://ir.archive.ubuntu.com natty InRelease                     
Ign http://extras.ubuntu.com natty Release.gpg                       
Ign http://security.ubuntu.com natty-security Release.gpg            
Ign http://ir.archive.ubuntu.com natty-updates InRelease             
Get:1 http://repo.percona.com lucid InRelease [11.5 kB]              
Ign http://repo.percona.com lucid InRelease                                    
Ign http://extras.ubuntu.com natty Release                                     
Ign http://security.ubuntu.com natty-security Release                
Ign http://ir.archive.ubuntu.com natty Release.gpg                   
Ign http://security.ubuntu.com natty-security/main Sources/DiffIndex 
Ign http://ir.archive.ubuntu.com natty-updates Release.gpg           
Ign http://repo.percona.com lucid/main Sources/DiffIndex             
Ign http://security.ubuntu.com natty-security/restricted Sources/DiffIndex
Ign http://ir.archive.ubuntu.com natty Release                                 
Ign http://extras.ubuntu.com natty/main TranslationIndex                       
Ign http://repo.percona.com lucid/main i386 Packages/DiffIndex       
Ign http://ir.archive.ubuntu.com natty-updates Release               
Ign http://security.ubuntu.com natty-security/main i386 Packages/DiffIndex
Ign http://repo.percona.com lucid/main TranslationIndex              
Ign http://security.ubuntu.com natty-security/restricted i386 Packages/DiffIndex
Ign http://security.ubuntu.com natty-security/main TranslationIndex            
Ign http://security.ubuntu.com natty-security/multiverse TranslationIndex      
Ign http://security.ubuntu.com natty-security/restricted TranslationIndex
Ign http://security.ubuntu.com natty-security/universe TranslationIndex        
Ign http://ir.archive.ubuntu.com natty/main TranslationIndex                   
Ign http://ir.archive.ubuntu.com natty/multiverse TranslationIndex   
Err http://extras.ubuntu.com natty/main Sources                      
  404  Not Found
Ign http://ir.archive.ubuntu.com natty/restricted TranslationIndex   
Err http://extras.ubuntu.com natty/main i386 Packages                          
  404  Not Found
Ign http://ir.archive.ubuntu.com natty/universe TranslationIndex               
Ign http://extras.ubuntu.com natty/main Translation-en_US                      
Ign http://extras.ubuntu.com natty/main Translation-en                         
Ign http://ir.archive.ubuntu.com natty-updates/main TranslationIndex 
Ign http://ir.archive.ubuntu.com natty-updates/multiverse TranslationIndex
Ign http://ir.archive.ubuntu.com natty-updates/restricted TranslationIndex
Ign http://ir.archive.ubuntu.com natty-updates/universe TranslationIndex
Hit http://repo.percona.com lucid/main Sources                       
Hit http://repo.percona.com lucid/main i386 Packages                 
Ign http://repo.percona.com lucid/main Translation-en_US             
Ign http://repo.percona.com lucid/main Translation-en                
Err http://security.ubuntu.com natty-security/universe Sources                 
  404  Not Found [IP: 91.189.92.201 80]
Err http://security.ubuntu.com natty-security/multiverse Sources                      
  404  Not Found [IP: 91.189.92.201 80]
Err http://security.ubuntu.com natty-security/universe i386 Packages                  
  404  Not Found [IP: 91.189.92.201 80]
Err http://security.ubuntu.com natty-security/multiverse i386 Packages                                         
  404  Not Found [IP: 91.189.92.201 80]
Err http://security.ubuntu.com natty-security/main Sources                                                                     
  404  Not Found [IP: 91.189.92.201 80]
Err http://security.ubuntu.com natty-security/restricted Sources                                                               
  404  Not Found [IP: 91.189.92.201 80]
Err http://security.ubuntu.com natty-security/main i386 Packages                                                               
  404  Not Found [IP: 91.189.92.201 80]
Err http://security.ubuntu.com natty-security/restricted i386 Packages                                                         
  404  Not Found [IP: 91.189.92.201 80]
Ign http://security.ubuntu.com natty-security/main Translation-en_US                                                           
Ign http://security.ubuntu.com natty-security/main Translation-en                                                              
Ign http://security.ubuntu.com natty-security/multiverse Translation-en_US                                                     
Ign http://security.ubuntu.com natty-security/multiverse Translation-en                                                        
Ign http://security.ubuntu.com natty-security/restricted Translation-en_US                                                     
Ign http://security.ubuntu.com natty-security/restricted Translation-en                                                        
Ign http://security.ubuntu.com natty-security/universe Translation-en_US                                                       
Ign http://security.ubuntu.com natty-security/universe Translation-en                                                          
Err http://ir.archive.ubuntu.com natty/main Sources                                                                            
  404  Not Found [IP: 91.189.92.200 80]
Err http://ir.archive.ubuntu.com natty/restricted Sources
  404  Not Found [IP: 91.189.92.200 80]
Err http://ir.archive.ubuntu.com natty/universe Sources
  404  Not Found [IP: 91.189.92.200 80]
Err http://ir.archive.ubuntu.com natty/multiverse Sources
  404  Not Found [IP: 91.189.92.200 80]
Err http://ir.archive.ubuntu.com natty/main i386 Packages
  404  Not Found [IP: 91.189.92.200 80]
Err http://ir.archive.ubuntu.com natty/restricted i386 Packages
  404  Not Found [IP: 91.189.92.200 80]
Err http://ir.archive.ubuntu.com natty/universe i386 Packages
  404  Not Found [IP: 91.189.92.200 80]
Err http://ir.archive.ubuntu.com natty/multiverse i386 Packages
  404  Not Found [IP: 91.189.92.200 80]
Err http://ir.archive.ubuntu.com natty-updates/main Sources
  404  Not Found [IP: 91.189.92.200 80]
Err http://ir.archive.ubuntu.com natty-updates/restricted Sources
  404  Not Found [IP: 91.189.92.200 80]
Err http://ir.archive.ubuntu.com natty-updates/universe Sources
  404  Not Found [IP: 91.189.92.200 80]
Err http://ir.archive.ubuntu.com natty-updates/multiverse Sources
  404  Not Found [IP: 91.189.92.200 80]
Err http://ir.archive.ubuntu.com natty-updates/main i386 Packages
  404  Not Found [IP: 91.189.92.200 80]
Err http://ir.archive.ubuntu.com natty-updates/restricted i386 Packages
  404  Not Found [IP: 91.189.92.200 80]
Err http://ir.archive.ubuntu.com natty-updates/universe i386 Packages
  404  Not Found [IP: 91.189.92.200 80]
Err http://ir.archive.ubuntu.com natty-updates/multiverse i386 Packages
  404  Not Found [IP: 91.189.92.200 80]
Ign http://ir.archive.ubuntu.com natty/main Translation-en_US
Ign http://ir.archive.ubuntu.com natty/main Translation-en
Ign http://ir.archive.ubuntu.com natty/multiverse Translation-en_US
Ign http://ir.archive.ubuntu.com natty/multiverse Translation-en
Ign http://ir.archive.ubuntu.com natty/restricted Translation-en_US
Ign http://ir.archive.ubuntu.com natty/restricted Translation-en
Ign http://ir.archive.ubuntu.com natty/universe Translation-en_US
Ign http://ir.archive.ubuntu.com natty/universe Translation-en
Ign http://ir.archive.ubuntu.com natty-updates/main Translation-en_US
Ign http://ir.archive.ubuntu.com natty-updates/main Translation-en
Ign http://ir.archive.ubuntu.com natty-updates/multiverse Translation-en_US
Ign http://ir.archive.ubuntu.com natty-updates/multiverse Translation-en
Ign http://ir.archive.ubuntu.com natty-updates/restricted Translation-en_US
Ign http://ir.archive.ubuntu.com natty-updates/restricted Translation-en
Ign http://ir.archive.ubuntu.com natty-updates/universe Translation-en_US
Ign http://ir.archive.ubuntu.com natty-updates/universe Translation-en
Fetched 1 B in 20s (0 B/s)
W: GPG error: http://repo.percona.com lucid InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 1C4CBDCDCD2EFD2A
W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/natty/main/source/Sources  404  Not Found
W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/natty/main/binary-i386/Packages  404  Not Found
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/natty-security/universe/source/Sources  404  Not Found [IP: 91.189.92.201 80]
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/natty-security/multiverse/source/Sources  404  Not Found [IP: 91.189.92.201 80]
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/natty-security/universe/binary-i386/Packages  404  Not Found [IP: 91.189.92.201 80]
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/natty-security/multiverse/binary-i386/Packages  404  Not Found [IP: 91.189.92.201 80]
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/natty-security/main/source/Sources  404  Not Found [IP: 91.189.92.201 80]
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/natty-security/restricted/source/Sources  404  Not Found [IP: 91.189.92.201 80]
W: Failed to fetch http://ir.archive.ubuntu.com/ubuntu/dists/natty/main/source/Sources  404  Not Found [IP: 91.189.92.200 80]
W: Failed to fetch http://ir.archive.ubuntu.com/ubuntu/dists/natty/restricted/source/Sources  404  Not Found [IP: 91.189.92.200 80]
W: Failed to fetch http://ir.archive.ubuntu.com/ubuntu/dists/natty/universe/source/Sources  404  Not Found [IP: 91.189.92.200 80]
W: Failed to fetch http://ir.archive.ubuntu.com/ubuntu/dists/natty/multiverse/source/Sources  404  Not Found [IP: 91.189.92.200 80]
W: Failed to fetch http://ir.archive.ubuntu.com/ubuntu/dists/natty/main/binary-i386/Packages  404  Not Found [IP: 91.189.92.200 80]
W: Failed to fetch http://ir.archive.ubuntu.com/ubuntu/dists/natty/restricted/binary-i386/Packages  404  Not Found [IP: 91.189.92.200 80]
W: Failed to fetch http://ir.archive.ubuntu.com/ubuntu/dists/natty/universe/binary-i386/Packages  404  Not Found [IP: 91.189.92.200 80]
W: Failed to fetch http://ir.archive.ubuntu.com/ubuntu/dists/natty/multiverse/binary-i386/Packages  404  Not Found [IP: 91.189.92.200 80]
W: Failed to fetch http://ir.archive.ubuntu.com/ubuntu/dists/natty-updates/main/source/Sources  404  Not Found [IP: 91.189.92.200 80]
W: Failed to fetch http://ir.archive.ubuntu.com/ubuntu/dists/natty-updates/restricted/source/Sources  404  Not Found [IP: 91.189.92.200 80]
W: Failed to fetch http://ir.archive.ubuntu.com/ubuntu/dists/natty-updates/universe/source/Sources  404  Not Found [IP: 91.189.92.200 80]
W: Failed to fetch http://ir.archive.ubuntu.com/ubuntu/dists/natty-updates/multiverse/source/Sources  404  Not Found [IP: 91.189.92.200 80]
W: Failed to fetch http://ir.archive.ubuntu.com/ubuntu/dists/natty-updates/main/binary-i386/Packages  404  Not Found [IP: 91.189.92.200 80]
W: Failed to fetch http://ir.archive.ubuntu.com/ubuntu/dists/natty-updates/restricted/binary-i386/Packages  404  Not Found [IP: 91.189.92.200 80]
W: Failed to fetch http://ir.archive.ubuntu.com/ubuntu/dists/natty-updates/universe/binary-i386/Packages  404  Not Found [IP: 91.189.92.200 80]
W: Failed to fetch http://ir.archive.ubuntu.com/ubuntu/dists/natty-updates/multiverse/binary-i386/Packages  404  Not Found [IP: 91.189.92.200 80]
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/natty-security/main/binary-i386/Packages  404  Not Found [IP: 91.189.92.201 80]
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/natty-security/restricted/binary-i386/Packages  404  Not Found [IP: 91.189.92.201 80]
E: Some index files failed to download. They have been ignored, or old ones used instead.
وقتی می زنم sudo apt-get install apache2 :
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package apache2