Some suggestions:

- Try safe mode / recovery mode or last known good boot
- If you're unable to log on locally, maybe you can connect over the network. If you have terminal services (Win2k server), try that.
- Alternatively try connecting with Windows File Sharing. If you can get in over that, establish a session as administrator (try net use q: \\machinename\c$ /user:administrator or something), then maybe you can use "Computer Management" (Win2k) or "Server Manager" (NT4) to remotely restart whatever services you've shut down accidentally.

- If that fails, maybe you can log into SQL server as "sa" (Assuming you've got mixed-mode authentication on SQL 2000) and the using xp_cmdshell you can run "net start" to start the appropriate services?

- If that fails too, but you still have some way of getting files in, you could write a CGI program, CGI script or ASP page (possibly?) which runs "net use", then connect to the IIS web server, login as administrator as a web login and run that script (which should then run as administrator, hence be able to start services)

- If that fails too, things are getting a little tricky

- I will come up with some more ideas if those all fail ...