|First, the file is called /etc/passwd, not /etc/password. You should see your account name in the results of "tail /etc/passwd".|
If Ubuntu uses GRUB, and I'm reasonably sure it does, all you have to do is press "e" when it briefly pauses before booting. You will then be able to edit the boot options. Go to the end of the line and enter "init=/bin/bash". This will bypass all startup procedures and give you root access. Run the "tail /etc/passwd" command I mentioned earlier to identify your username. Your root filesystem will be mounted readonly, so you'll want to run "mount -o remount,rw /". Then set your password with "passwd yourusername".
It's possible to password protect GRUB. If you encounter this, use Paracomp's method. You will need to edit etc/shadow. If you completely remove the longest string of junk between two colons, your password will be removed. Reboot, login, and set a new password with "passwd".