Fullscreen has black bars.

I have a 2560 x 1080 moniter. For the past year i have been unable to get rid of black bars on my screen. I have resorted to playing 1680 x 1060 windowed. If anyone can fix this im willing to get like a 10$ game on steam or something for them. Any help is appreciated. Please dm me. Game worked properly on my 1920 x 1080 moniter btw (It broke which is why I got a new one).