Thanks a lot for your reply. Yes there was an error message but i got a suggestion to change the name of the computer and then switch from the domain to a workgroup which i did. I later on changed to the original name and joined it again to the domain and i am now able to log in perfectly
Once again thanks for your concern
That would do it if the PC somehow fell off the domain, but without knowing what the error message is, issue could have been several things.