I was working on my system when suddenly I was no longer able to use the sudo command. It was acting as if I was not entering the password correctly. I rebooted and found that I cannot log into my account anymore. I logged into another account and that works fine. This other user does have sudo access so I tried changing my first accounts password but to no avail. I know for a fact I'm typing the right password. Does anyone have any ideas as to what could cause this?
I can't tell you the cause, but you may change the other user's password without having to know it if you have root access (or access to an admin account who may use
sudo, as you described):
sudo passwd USERNAME
sudo will ask you first for your current account's password. After that you have to enter the new password for
USERNAME twice. Note that none of the password inputs will be echoed, that means you see nothing while typing, not even asterisks.
Example transcript (running as user
alphawolf, changing password of user
alphawolf@wolf-pack:~$ sudo passwd bytecommander [sudo] password for alphawolf: Enter new UNIX password: Retype new UNIX password: passwd: password updated successfully alphawolf@wolf-pack:~$