Tried Fprint, was stupid enough not to backup the common-auth file before changing it. Somehow I'm locked out of the system, trying to fingerscan doesn't do any difference. Even when I've done it 5 times and it asks for password, when it asks for password and I write it in and it says that it's the wrong password. I use the same password for root as for my user.

Tried to go into Recovery Mode -> root -> sudo nano /etc/pam.d/common-auth and remove the rows saying that you need the fingerprint to login, but when I try to overwrite, it says the file is read only, even when I try to open it with root.

I have a lot of schoolwork files and programs on the system, so I can't afford losing them. Help?