As the title says, the fan on my PSU is not working and thanks to that, my PC overheats and it turns off after playing a game like CoD. My question is, is the fan broken or did i mess something up in BIOS? Can it be fixed? And if not, which 500 - 600 W power supply do you suggest?
You can always take your current power supply to a technician for check up. There might be an uprooted wire which may be causing the fan to not spin at all. I just recommended a new PSU as your current one looks generic.
As for recommending a PSU, we need to know your budget first. Blind guessing, I can suggest you to get a Corsair TX 650 V2 which will be plenty for any single video card build (and some multiple video card builds also).