If you can't access your system, from the Grub 2 menu: Press ENTER after each line; are just clarifying comments - do not type them.
Code:
enter command line mode
set root=(hd0,1) # to set sda1 as root
linux /vmlinuz root=/dev/sda1 ro
initrd /initrd.img
boot
Once into the system, open /etc/default/grub:
Code:
sudo gedit /etc/default/grub
You can try disabling the UUID function to see if that solves things for you :
GRUB_DISABLE_LINUX_UUID=true
Update Grub2:
Code:
sudo update-grub
