Mercedes: 300 CE 88 power windows, door hinge, window switch

Question
The all four power windows suddenly stop working.
I've checked fuses and relay and it's ok .
What else it could be ?

Thank you  

Answer
Cassio,
You may have a high resistance connection or a loose connection. There may be a relay in the window circuit that is out. A schematic diagram would tell you about the window circuit.
In addition you may have a window switch, that has gone bad.
There is a possibility that wire in the harness has broken. I had this issue on a vehicle where the wire passes from the body door frame passed the door hinge and into the door.
If you have a central console to operate the four windows, then I would look at that first.
Good Luck
Rob