Well I think we need more info. For example will the system allow a
user in if he or she does not enter the password?
Tried changing the users password with the passwd command? Will it at
least let root in?

i'm just getting the login prompt.After i enter the login id i
should be getting passwd prompt,which i'm not getting !!!!
how could login into the system now ??

do you have web server on ? or ftp ? or other services which you
require to log on ? - pls verify if they work
maybe just login process is dead, or (pray not to) your
/etc/thefileyoukeepthepasswords is dead & gone
(try booting in rc1)

Can You please check whether tha passwd file and Shadow file excist in the
/etc directory......

If you can, boot into single-user mode tocheck out that passwd file. That will avoid needing a password and after typing in your root account name, drop you into command-line mode.

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Boot into single user mode. "linux single" at the boot: prompt.

Alternatively I think you can use your Mandrake CD as an emergency disk
to get around it.