Hm. This sounds like a video card, monitor issue or Windows problem. Nvidia or AMD drivers? No matter, load the current drivers available from those sites, load them, and then restore the individual monitors to their factory settings (this is found on the monitor itself, press a button typically and a small window will appear on the monitor that is monitor driven).
Next. In the Windows Control panel there is a subheading ‘Display’. Go to ‘screen resolution’ under this heading and you should see your two monitors. Number them correctly, etc., and you should be up and running. If one of your monitors is broken (fuzzy image?) just swap monitor inputs to confirm. Replace as necessary.
Good luck.