A lot of people may have had this kind of problem. "grub rescue>" appears because of the non-existent of "grub.cfg". Why? Normally, It is caused by the users who accidentally deleted the installation partition for the OS Linux including the file "grub.cfg".
There are many ways to solve this problem. Some of you may want to use the Live CD of Windows (if you are Windows user), and there are other people who choose to use the OS Linux Live CD such as the Backtrack or Ubuntu or any other types of Linux OS.
But, how if I don't have any Live CD? Relax. Please try the steps below, and good luck.
Continue with these commands.
If the system gives you warning that the insmod couldn't be recognized, you have to repeat from step two and choose another partition.
If there is no problem, you will see many commands which run automatically and the system will ask you to enter the username boot login "root" and the password "toor". In case you have problem, you have to repeat from step one and choose another partition.
And then, run your backtrack "startx"
Open the terminal window in Backtrack.
Finally, restart your computer.
Happy coding. Good luck :)
FYI. I have no idea whether this kind of troubleshooting can be implemented in any other types of Linux OS. Because, I've only tried it in Backtrack. Thank you.