Blank Screen on start up, nothing loads

Hello,
My hp touchsmart desktop froze (into a black and white patterned screen) while in use after i plugged a phone charger into wall socket next to the one the computer was plugged in at, but i didnt plug it into the computer/touch the computer cable or plug. so i turned it off and now when i turn it back on the computer starts up but the screen stays blank (nothing loads up at all). at the time my usb memory stick was plugged into the computer and i removed this only after i had turned the computer off. could this be due to overheating as i had the computer on for several hours working before this happened? although it is usually left on (sleep mode) nearly all the time. is there any way that i can fix this quickly myself (lots of uni work due in tomorrow etc) any possible solutions/help or even if anyone knows what the problem may be would be greatly appreciated!!! if anymore details are needed for anyone to suggest a solution i will tell you but i think ive pretty much covered everything that happened to it! i dont really know what category this falls into so ive just put it in the systems one is as i am very bad with computers so im hoping someone can help please!!