Possible Duplicate:
Can't boot without Flash Drive plugged in
My problem is very much like the problem described in the link.
I have FreeDOS and Ubuntu 12.04. When I boot without bootable USB the computer simply proceeds to DOS. With USB stick I have to enter ubuntu via BIOS.
I WISH TO REINSTALL Ubuntu. What is the procedure to reinstall ubuntu from ubuntu itself?
Or is there any other solution to the problem?