In general,you can make it by the following method:

First you can check the device management of your computer whether there is a Bluetooth device with a question mark (right click on "Computer" before you click on "Management" and click on "Device Manager" on the left). If so, you can download and install the Bluetooth driver on the download page of the official website of your computer brand. If it's not found, go to bios--config--network to see if the device is enabled, otherwise it  may be a hardware failure.If it is normal, it should be the setting problem of your computer system.

Or you can reinstall the driver for the network card.

 If it can't still be solved,you can just reinstall the system of your desktop.Please note: don't install a Win 7 system of the pure version,which may cause some of  your problems. May you succeed.