Are you using digital audio out like S/PDIF or HDMI to receiver then Head Phones? Or just 3.5mm Plug directly to PC..?
If normal 3.5mm to PC, make sure 1st it’s definitely the correct port. Double check in windows settings
Also check manual and online support as a fair few have multi purpose plugs and have to be change or set with supporting software.
really sounds like you’ve either plugged your Hphones into one of the L+F stereo plugs, one of the channels possibly for 5.1 - 7.1 speakers or possible faulty cable, plug etc..?
Heres a quick Screen of the settings / options I can think to check..
Check,p these menu’s & options and double check your Manual incase you have set within application..