Have you tried to reinstall grub from liveCD, as explained in https://help.ubuntu.com/community/Grub2#Reinstalling%20from%20LiveCD
This worked for me -- grub2 file not found error https://bugs.launchpad.net/bugs/355359 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
