Rolling back the drivers doesn't work, but I found another solution.  I connected to the internet via ethernet, and then in the device manager told windows to search for drivers online, which then fixed the problem.
The precision 5520 is available with two wireless cards, the dell wireless 1820 (when configured with ubuntu) and the Intel WiFi Link 8265 (when configured with windows 10).  I have the 1820 and ubuntu, but I also want to use windows 10.  When I installed windows 10, the card worked fine.  However, when I installed the anniversary update, the card stopped working.  In the device manager, it said that the device cannot start (code 10).  On the dell website, there are only drivers listed for the Intel WiFi Link 8265 card, and none for the 1820, so I couldn't install any drivers.   Does anyone know how to make the 1820 card work under windows 10 anniversary?
Dell Precision 5520 with Dell wireless 1820 in Windows 10 anniversary