Please refer to the following FAQ for troubleshooting.
Sorry for any inconvenience it may be caused.
Shut down your PC. Press the power button and immediately press F2 to enter into BIOS setup. Press F9 (or the load defaults button shown on the BIOS screen) to reset your BIOS. Press Esc or F10 and select “save and Exit” press Enter and allow your system to restart then check if the fan now works.