Your Grub menu is missing some major components, but we should be able to boot from the grub prompt and then rebuild the grub.cfg file.
At the grub prompt:
I believe the necessary modules are already loaded. If you get an error message about a missing module, run this command with the module name:
linux /vmlinuz root=/dev/sda5 ro
Once it boots, run
then run this command to see if the proper menuentries were generated. You should have at least one menuentry with "3.0.0-15-generic" as an available kernel.
I see you have some 10_linux proxy files - perhaps you tried Grub Customizer?
grep "menuentry" /boot/grub/grub.cfg
Make sure your scripts in the /etc/grub.d folder are executable if you still don't have at least one menuentry:
sudo chmod +x /etc/grub.d/10_linux /etc/grub.d/30_os-prober