I noticed that one of the fans in my computer was not spinning so I opened it up to have a look at it. I left it open so I could take the fan to a shop for a new one.
I started my computer, and it said "no input signal" on my monitor. I thought, "better put the fan back in", and I did so. However, even after I put it back in, the monitor still does not work, saying "no input signal".