Try this:
You can log in using single-user linux mode.
To enter Linux single-user mode, reboot your computer. If you use the default bootloader, GRUB, you can enter single user mode by performing the following:
1. At the bootloader menu, type [e] to enter into editing mode.
2. You will be presented with a boot entry listing. Look for the line that looks similar to the following:
kernel /vmlinuz-2.4.18-0.4 ro root=/dev/hda2
3. Press the arrow key until this line is highlighted and press [e].
4. You can now add single to the end of the text to tell GRUB to boot into single-user Linux mode. Press [Enter] to make the editing change take effect.
5. You will be brought back to the edit mode screen. From here, press [b] and GRUB will boot single-user Linux mode. After it finishes loading, you will be presented with a shell prompt similar to the following:
sh-2.05#
6. You can now change the root password by typing
bash# passwd root
7. You will be asked to re-type the password for verification. Once you are finished, the password will be changed and you can reboot by typing reboot at the prompt; then you can log in to root as you normally would.
To un-install Linux, follow
these instructions.
Let us know how you get on.