Computer powering up but no display.

Now I know there are about a hundred of these threads made and after looking through each one I still can't find a solution to my problem.

For the past two months my computer has randomly cut the connection to the display on my monitor. The computers power will still be on but the display on my monitor would just cut off and go black. After this happens I turn of the computer and then retry to start it up again and the computer would power up but my display would not come on. It would just remain a blank black screen. Now after I try to restart it again a few times it finally works. Also sometimes when it starts up again after my computer has loaded in and I get past the bios or whatever right before I get to the windows loading in screen it says an error has occurred trying to load windows. Something along the lines of not being able to load a system file. I restart again and redo the process and my computer then works fine after.

Also it's only happened twice but as I started up my computer it beeped more then four times. This only happened twice. This has only happened in these two months.

Also the ports I use in the back for my mouse and keyboard seems to be losing the connection. Sometimes I have to wiggle them around and it finally stays on, also it does this for every USB in the back no matter which one I plug it into. Now they don't even turn on when I power up my Computer unless I seriously wiggle them around and I can see the light on my mouse going on and off but it never stays on for more then half a second , this happens during the black screen.

Now we come to today where I restarted my Computer and it now the problem won't go away. I turn on my computer and the power turns on but no display.

Things I've tried doing. I've unplugged everything and removed the little battery for ten minutes and replaced it. Tried un hitching both rams, I've tried keeping one in and taking the other out and back and forth. I've tried switching my graphics cards with my older ones. I've completely cleaned out the inside free of dust and other things.

Also a side note when I was undoing the fan on the heatsink above my CPU
The heatsink literally was not attached to the bottom part and could be moved freely, I could see the signs of the paste from before still on the bottom and on top of the CPU but it was clearly gone from time. I have no clue if that is the problem

All the fans work, there are no lights on the motherboard so I can't tell anything about that. And the computer does not beep at all like I said before.

I'm not a computer kind of guy and from reading over the many threads I've come to the conclusion that perhaps because my heatsink wasn't properly on for a while, maybe since I got it two years ago, the CPU has overheated and cause the board to go bad. Like I said there are no beeps at all. I hope someone can either agree with me or tell me what's wrong because I have no idea.