Probably something is wrong with your /etc/apt/sources.list
document. You should remove your PPAs, because it seems that someting is wrong with them. Open a terminal (Strg + Alt + T) and type sudo nano /etc/apt/sources.list
. After you've entered your password, you can see all the PPAs and official repositorys.
The standard sources.list file looks like this:
deb http://de.archive.ubuntu.com/ubuntu quantal main restricted universe multiverse
#deb-src http://de.archive.ubuntu.com/ubuntu quantal main restricted universe multiverse
deb http://de.archive.ubuntu.com/ubuntu quantal-updates main restricted universe multiverse
#deb-src http://de.archive.ubuntu.com/ubuntu quantal-updates main restricted universe multiverse
deb http://de.archive.ubuntu.com/ubuntu quantal-security main restricted universe multiverse
#deb-src http://de.archive.ubuntu.com/ubuntu quantal-security main restricted universe multiverse
deb http://de.archive.ubuntu.com/ubuntu quantal-backports main restricted universe multiverse
#deb-src http://de.archive.ubuntu.com/ubuntu quantal-backports main restricted universe multiverse
So, delete all the entries and paste the repositorys above into the file. Then press Strg + O for saving changes and than Strg + X for exiting.
Please remark, that all your manually added PPAs are deleted in this way. But you can add them later again, if you have updated your programs.