I was trying to upgrade my 2nd computer's hard drive, and in the process, I un-admin'd and disabled my account. I'm using the guest account right now. I've tried everything that ask ubuntu has to offer (or at least after 5 hours of searching, trying, and failing) i.e., creating a new account (didn't allow me to do it), usermod, passwd, anything involving sudo, hell, I can't even get into recovery mode with the left shift thing... I really want to get into my account. Please help me.
Adding Users To Admin / Sudo Group Using Recovery Mode
First shutdown your computer, then 'restart whilst holding shift' on the keyboard to load grub menu.
Select 'recovery mode' from the grub menu.
Select 'drop to root shell' from the recovery menu.
Remount the drive with write permission using
You should now see a message saying 'adding user' followed by 'done'.