I recently installed a Ubuntu 10.10 for my friend, and during the installation, I picked a random password and turned out I could not spell it again after finishing the installation.
There are quite many posts on the Internet if you search “forgot password ubuntu“. And the solution is quite easy for Ubuntu 10.10.
1, Reboot the computer, go to recovery mode in the GRUB memu ( if Ubuntu is the only OS, hold shift key to show the GRUB menu. )
2, In the recovery menu, select root or netroot
3, In the terminal, type passwd yourusername
4, Enter new password twice…
5, reboot -f
And that’s it.
Changing the password is so easy and may be I would like to hide my recovery mode in GRUB.