Laptop has given up

First it started when I tried upgrading to windows 10. It didnt upgrade properly so the usb drivers went missing, tried to get it back by downloading rubbish driver pack online instead kept downloading virus. Long story short it gave me a blue screen saying no boot media or file found. Had to take it back to windows 7ultimate because it couldn't find the windows 8.1 that originally came with it. Was trying again to update the and that went missing along with the usb driver, downloaded trash again then tried recoverying from last back up and now blank screen. The power light comes on, you can hear and feel the fan but blank screen. Help me