Windows 2000 Login re-appears again and again - Administrator

Windows 2000 Login re-appears again and again - Administrator

Hi, I have a windows 2000, by error got delete one of the system files and now I could not go into desktop.. the system starts up and then goes to the login level..Reapprears once entered.. it returns back to login menu again and again.

I want to install the missing file..

please suggest, will your boot disc work.. if so..

I want to copy to a cd and burn.. can you provide me some details please

thank you in advance.
J.L