All of a sudden my keyboard stopped working on my Dell desktop (XPS 420). I changed the batteries, checked whether the keyboard was working properly (under Control Panel - it was according to the computer) but nothing changed. I pressed the bluetooth button on the back and the blue light continued to flash but nothing happened. I checked to make sure the drivers were up to date and they were. I went through all the usual troubleshooting but nothing worked.

I rebooted but now I can't even get past the Login screen because neither the bluetooth mouse or the keyboard are connecting so I'm stuck. I suspect that the bluetooth module (?) or hardware might be broken but I'm hoping it isn't. Any idea what I can do to fix this? 

Thank you!