You could try RESTORE GRUB (use your HD and partition numbers)
1. Pop in the Live CD, boot from it until you reach the desktop.
2. Open a terminal window
3. Type "grub
4. Type "root (hd0,6)
", or whatever your harddisk + boot partition numbers are (my /boot is at /dev/sda7, which translates to hd0,6 for grub).
5. Type "setup (hd0)
", or whatever your harddisk number is.
6. Quit grub by typing "quit
or download the SuperGrub Live CD:http://linuxmint.com/forum/viewtopic.php?f=90&t=6875&p=43655#p43655
I hope one of these can get you out of your problem.