I have just installed Lubuntu 14.04 and can't log in. I get incorrect password, even though I just added and confirmed password during setup. I did not set up any users during setup just a root password.
Do you know how to fix this problem?
By default while installation ubuntu does not set root password. It creates a default User, based on what you enter in "Enter your Name" , and sudo rights are given to it.
Double check if your caps lock was on and try to login from shell (Ctrl+Alt+F1/F2), not with "root" as username.
At the grub login, drop to root shell and either check if your user is in /etc/passwd and change the user password or add your user.