1999 Chevy Blazer

I have a 1999 Chevy Blazer with 4X4 issues 4 switch in dash. Only the 2Wheel lite is on and I try the 4High or 4Lo or auto won't engage when they are pushed and my service 4WD lite is on. I've been pulling my hair out to figure this out. I tried a different switch in the dash it did the same thing.What could this be could you help me. I'm sorry I can't donate anything. But I've been laid off. I worked in a Trailer factory in Indiana. And I have no call back. And I have had no income. Thanks What is the most common problem.