|If your system is not accepting any password then check if you are giving the right password or not by the following method.|
When the loginn screen appears press
Type password. (Don't panic if nothing appears on screen)
Does it log you in?
If no then you have forgot your password and ask your system administrator to change your password.
If yes then type
Try the same username and password you just applied.
Does it work?
If no then try reinstalling Linux.
Best of luck.
National Institute of Technology