The two front power windows quit working on my 1993 STS. I replaced the master door switch on the drivers door just as a possibility with no success. The passenger window does not work with either switch. Because of them both failing at the same time I'm thinking possibly a relay somewhere? Any suggestions on where to go from here?
The first thing you need to do is check and trace the wiring.
As for the wiring, you need to see if you even have power going to the main switch. If you don't, that would also explain why the other switch doesn't work. The one thing I stress because I have repaired hundreds of times is these are notorious for breaking wires inside the rubber boot at the front of the door at the pinch point.
When people are trying to fix these old cars I highly recommend the factory service manual. This way you get diagnostics, wiring schematics and everything you need to do your own repairs. Could cost hundreds if you can even find one. You can do what I do. I can download the manual for a year for $30. How much did you spend on the switch that did not fix the problem?
Go here http://www.alldata.com