NT 4.0 workstation lockout

I used the NT 4.0 cd to repair a ntldr missing error and now that I have done that I am locked out of the system. I tried both th edomain and local passwords to no avail (the system can not log you on C00000DF) error message. It is as if The pc is not on the network because It does not show on the network server manager. Help!!

Thanks.