HP Laptop doesnt start up

Hello, I was using my laptop (HP G70 something, I cant find the box it came in) which was working fine. I turned it off to clean underneath the keys with a can of compressed air. I took a few of the keys off and had no trouble getting them back on. I turned my laptop on, and once it goes past the HP screen, it stays blank. I've even tried doing a system restore, but it stays blank. Does anyone have any suggestions that could get it working again?

Thank's :)