upgrade 11.04 to 11.10 no response about available release by update manager

If you want to upgrade, you would be far safter not to try upgrading from the update manager. To upgrade, download the iso, burn a DVD and boot from this. It gives you the option to try unbuntu without installing. Run this option and check that everything works before even thinking about installing. Then if you want to go ahead and install shut the computer down, re-boot and make sure you have backed up all data. If you have another operating system on the same drive make sure everything there is backed up too. If something goes wrong during upgrade, it can affect everything on your drive.

I recommend that you carry out a clean install rather than trying to use the upgrad option. Your data wikk be lost, but it can be quicker and easier to restore data than fix a broken system if things do not go as planned. Any problems on 11.04 that you have will cause bigger problems on the new system if you simply upgrade.

Please ask before committing if you are even slightly unsure. Upgrading is never a 100% safe process on any operating system.

Please open a terminal and try:

sudo dpkg --configure -a
sudo apt-get -f install
sudo apt-get autoremove
sudo apt-get clean
sudo apt-get update
sudo apt-get upgrade
sudo apt-get dist-upgrade

sudo apt-get clean
sudo apt-get autoremove

Please check if the system require a reboot... (needed on kernel upgrade) then try to upgrade the system with this terminal command:

sudo do-release-upgrade