Monitor won't show anything after random shut down

[GuitarDTC]

My computer has been messed up for about a year. i got a virus from downloading a program (called fire letters or something) and my computer shut down right after i installed it. i turn it back on and found out i can't go on the internet. As soon as i try to open internet explorer, an error message comes up and the browser closes. i tried with firefox and the same thing happened. I start playing games on my computer and in the middle of playing, the computer would shut down randomly, not very often and then later, unbearably often. i tried a virus protection software ( something like norton antivirus) for $40 at best buy. i would try to scan my computer, it would say that it is scanning, but the files scanned would always say zero. After a while i just gave up on the computer. A couple days ago, i wanted to try and use it again. It didnt shut down randomly but still no internet. i used it for about 3 days when, after being gone for a while, came back and notice it randomly shut down. I turn it back on. it starts to run for about a minute and shuts down again. when it shuts down, a red light starts flashing on the monitor. I looked up online what i could do about the shutting down problem and someone said overheating, and for some reason i thought dust could be the problem. i open up my comp and see tons of dust. I then use compressed gas duster to blow all the dust out of the computer. i i plug everything back in and try to start it. the computer starts up ( i hear the fan, lights on keyboard turn on, ect) but my monitor stays black. There is the little red light blinking in the monitor corner. i turn off the monitor, and then back on, i hear the static thing in the back, the green light comes on, but then right away switches to the blinking red. Please help!

 

[Tmagic650]

What are your computers specs? Make and model? Operating system? You may have to reformat the hard drive and re-install Windows fresh, if you can't restore to factory settings