Hi JamesTB1,
The receiver or the USB device for the wireless mouse and keyboard comes pre-installed in a compartment found on the lower left hand side corner of the system.
You may try reseating the the dongle. Please ensure the keyboard and mouse have new batteries. You may try to re-pair the keyboard and mouse with the system. You may refer to the following link for steps:
Hope this helps. Feel free to reply in case you need any further assistance. I will be happy to help.