1992 Other Mercedes Benz Models several different features n

Interior problem
1992 Other Mercedes Benz Models 6 cyl Two Wheel Drive Automatic

After a backyard mechanic worked on my friends car (engine rebuild) the drivers window, sunroof, and rear window defogger stopped working. And the stereo will not turn on, but it keeps flashing enter code and my friend knows nothing about it since she bought it used and doesn't know anything about the car. I figured the stereo just needs this "code" to work but how do I do that? And would a fuse explain just the drivers window, sunroof and rear w/defog not working? Any tips?