Neither one of my back windows will roll down. I just bought the car in April so I have no idea the history of this.. any ideas why they won't work??

All my fuses are good, the other windows work..

 

Do they not go down at all, or do they not go down using the back door switches? There is (at least on my A6) a switch on the drivers door which disables the switches on the back doors. If this is set incorrectly (or broken) the back windows will only work from the drivers door.

 

Try fuse no. 17. That powers the rear windows while fuse 16 powers the front.