Suddenly can not apt-get update

[saulius0317]

Hej!

I'm a beginner. Got Linux Sarge. Everything was working fine for months, but suddenly apt-get update and apt-get upgrade stoped working. When execute first get:

serveris:~# apt-get update
Err http://security.debian.org stable/updates/main Packages               
  Temporary failure resolving 'security.debian.org'
Err http://ameba.sc-uni.ktu.lt stable/main Packages                       
  Temporary failure resolving 'ameba.sc-uni.ktu.lt'
Err http://security.debian.org stable/updates/main Release                
  Temporary failure resolving 'security.debian.org'
Err http://ameba.sc-uni.ktu.lt stable/main Release                        
  Temporary failure resolving 'ameba.sc-uni.ktu.lt'
Err http://ameba.sc-uni.ktu.lt stable/main Sources
  Temporary failure resolving 'ameba.sc-uni.ktu.lt'
Err http://ameba.sc-uni.ktu.lt stable/main Release
  Temporary failure resolving 'ameba.sc-uni.ktu.lt'
Failed to fetch http://ameba.sc-uni.ktu.lt/debian/dists/stable/main/binary-i386/Packages.gz  Temporary failure resolving 'ameba.sc-uni.ktu.lt'
Failed to fetch http://ameba.sc-uni.ktu.lt/debian/dists/stable/main/binary-i386/Release  Temporary failure resolving 'ameba.sc-uni.ktu.lt'
Failed to fetch http://ameba.sc-uni.ktu.lt/debian/dists/stable/main/source/Sources.gz  Temporary failure resolving 'ameba.sc-uni.ktu.lt'
Failed to fetch http://ameba.sc-uni.ktu.lt/debian/dists/stable/main/source/Release  Temporary failure resolving 'ameba.sc-uni.ktu.lt'
Failed to fetch http://security.debian.org/dists/stable/updates/main/binary-i386/Packages.gz  Temporary failure resolving 'security.debian.org'
Failed to fetch http://security.debian.org/dists/stable/updates/main/binary-i386/Release  Temporary failure resolving 'security.debian.org'
Reading Package Lists... Done
W: Couldn't stat source package list http://ameba.sc-uni.ktu.lt stable/main Packages (/var/lib/apt/lists/ameba.sc-uni.ktu.lt_debian_dists_stable_main_binary-i386_Packages) - stat (2 No such file or directory)
W: Couldn't stat source package list http://security.debian.org stable/updates/main Packages (/var/lib/apt/lists/security.debian.org_dists_stable_updates_main_binary-i386_Packages) - stat (2 No such file or directory)
W: You may want to run apt-get update to correct these problems
E: Some index files failed to download, they have been ignored, or old ones used instead.

when execute second get:

serveris:~# apt-get upgrade
Reading Package Lists... Done
Building Dependency Tree... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
W: Couldn't stat source package list http://ameba.sc-uni.ktu.lt stable/main Packages (/var/lib/apt/lists/ameba.sc-uni.ktu.lt_debian_dists_stable_main_binary-i386_Packages) - stat (2 No such file or directory)
W: Couldn't stat source package list http://security.debian.org stable/updates/main Packages (/var/lib/apt/lists/security.debian.org_dists_stable_updates_main_binary-i386_Packages) - stat (2 No such file or directory)
W: You may want to run apt-get update to correct these problems

sources.list contains:
#deb file:///cdrom/ sarge main
deb http://ameba.sc-uni.ktu.lt/debian/ stable main
deb-src http://ameba.sc-uni.ktu.lt/debian/ stable main
deb http://security.debian.org/ stable/updates main

have tried swedish sources but got the same?
what should I do?

thank you.

[Gimili]

Are you sure you have internet access?

[AndrewB]

check internet connection
then ping the servers
check they are still there, check the dir on the server is correct