Rebuilding the Workgroup
This only works for MacOS 9 and lower computers using Macintosh Manager.
At the login screen, select or type your username. Then type your password.
Before hitting return or the “Login” button, hold down the Apple and Option keys on the keyboard.
While still holding down the Apple and Option keys and click the “Login” button.
If prompted to select a workgroup, do so while still holding down the Apple and Option keys.
Keep holding down the Apple and Option keys until the computer asks if you want to rebuild the workgroup. Tell the computer to do so.
Wait for the login process to complete. It may take several minutes longer than usual.