Before you do any troubleshooting, ensure the wireless keyboard and mouse have been verified to be compatible with the Raspberry Pi.
Once you have verified your wireless keyboard and mouse are compatible, it is actually much easier to connect a wired USB keyboard and mouse to the Raspberry Pi, and then power on the Raspberry Pi. Once powered on, connect the wireless USB receiver to the Raspberry Pi. Typically, the wireless keyboard and mouse will work right away. If the keyboard and mouse do not immediately work, use the lsusb (list usb devices) command to verify that the wireless USB receiver is being recongized by the Raspberry Pi.
[root@server1 ~]# lsusb Bus 003 Device 004: ID 046d:c52b Logitech, Inc. Unifying Receiver