I have a G550 which works fine. I bought a Microsoft wireless keyboard and mouse and they work fine too.
Recently I had to take laptop on the road and I did not want to take the large wireless KB. But if I remove the little wireless USB thing, the keyboard and the touchpad on the laptop do not work. How do I fix this problem?
If the laptop keyboard and touchpad do not work, and only the Microsoft Wireless keyboard was working,it is a high possibility that the drivers that came from the wireless keyboard overwritten the drivers for your G550 built in keyboard and touchpad.
Go into Device Manager and uninstall the MS wireless keyboard
Unplugg the MS wireless receiver (the little USB thing)
Restart the computer, and the built-in keyboard and touchpad worked!!!
P.S. If you plug the MS wireless receiver back in again, the wireless KB and mouse will work again.