My pc stopped recognizing my phone when it is connected. How do I get that back? It used to show on windows explorer. Using system restore didn't help. Device Manager recognizes it, but with a yellow triangle symbol. When I delete it and re-connect it, it installs but then says the driver could not install because the device is not connected. (It IS connected). It used to show up in windows explorer and I have exchanged info from it to the PC.