You are running Windows Vista and don’t update to Service Pack 1 or a later version. The BIOS reduces power to the port which the input device is connected. You are using a portable or notebook computer that does not allow resume by using a Bluetooth device. The keyboard item in Control Panel is not configured to wake the computer when press a key on the keyboard. There is a system problem on your computer. The sleep key on your computer is not configured correctly. You can read the post 4 Solutions to Computer Won’t Wake up from Sleep Windows 10 to know the solutions.