PC won't display anything on the monitor

While I was using my PC it shut down on its own and tried to boot itself up.It started up for a few seconds then stopped then repeated. I shut it down and cleaned it then tried to turn it back on. It will turn on and the fans will run it no longer does the start stop anymore but nothing will come up on the monitor when I turn it on.
It also would emit a single beep on startup when it was working properly but now does not do that even though it is running.