How to fix RAM and VideoCards

Hi Experts,
Last night after I used my computer I shut It down, mostly I always left it open over night because I’m always downloading some stuff. I do not worry for overheating because my room is air conditioned. When I opened it this morning my monitor was very dark.
I couldn’t almost see my desktop. I shut down my computer and re-inserted my graphics card and re-plugged the monitor cable. When I open again my computer the problem was still there. I even set the monitor’s brightness but it won’t help me to solve the issue. Is my video card failing or the monitor itself? One thing I observed is that I hear annoying sound from my computer. Kindly help me to solve this problem anyone?
Thanks,
Jessica Soho
