cannot logon to win2k professional

Greetings,

i had a network domain in windows 2000 professional (The one that you
can set by right clicking 'my computer'). now I changed to workgroup
by selecting that option just below the domain one. I was asked to
restart. When i did so i couldnt logon to windows as it kwpt rejecting
the password. I just cannot logon to windows. Now the problem is also
that i dont have the dropdown option on the Logon Dialog box. I just
have User name and password field and the Ok and Cancel buttons. I
have tried pressing f8 during startup and have even reverted to last
known good configuration but to no avail...i just cant logon!...can
anyone help.

thanks,

atique