I was trying to upgrade to 12.04 LTS, but the upgrade froze in the process (it was stuck for over 8 hours) and I had to do a hard reboot. Now when I boot up, I get the following: mountall /lib/x86_64-linux-gnu/libc.so.6 version 'glibc_2.14' not found. I'm not sure what I need to do from here. Do I need to go back to the previous version? Or can 12.04 still be installed? I don't want to lose any of my files. I am still new to Linux, so please give detailed step-by-step instructions.