Boot Device Not Found

This laptop was not originally mine as it was handed down to me. The laptop has always worked fine and even would set up just fine however I was stupid and played around with it when I wanted to try to factory restart the laptop. Now whenever it turns on, it just says boot device not found, please install an operating system on your hard disk. If anyone can, please help figure this out because I really don't want to have to spend almost $1000 on a new laptop.