So my computer suddenly stopped working a few days ago.

The computer runs, and the monitor runs, but the monitor is not detecting the computer.
it says there is no vga or dvi detected, but the display went black and white line-y before the crash.

Was wondering if it was the video cable or whatever else.

I would have to assume that it is the cable, as the monitor itself works. Have you tried hooking the monitor to another computer and seeing what happens there? If it works with another system, then you know it's your tower, but if it doesn't, then you know the monitor is at fault. You can then proceed from there and either fix your computer or get another monitor.

Video cable, GPU, or monitor. Test with a different computer, test with a different cable. If a different computer works, then it's the GPU. If the GPU's not integrated, probably worth replacing it, or at least using a different port if it has one. If it is integrated, it's on the motherboard and it's a generally bad sign when a motherboard starts failing, and you probably want to replace the computer in some form or fashion, though it's pretty unlikely that that's actually the case unless your computer is ancient and has poor cooling and lots of dust. If neither a different cable or a different tower works, it's probably the monitor.

(Obviously, it could also be a weird driver issue or something like that. If so, good luck.)

Update: got a new video cable, that isn't the problem.
My keyboard isn't working either, but it isn't related to the ports.
Are those related?

This is a common problem. Its 80% of the BIOS fault.
Does your computer beeps when it boots? It should have a short beep, its a signal from your motherboard that everything is OK.

Try reseting CMOS, here is a guide.