How do I fix the Insert Media pop up?

I have a pop up when i'm trying to reboot my computer.

Insert Media.

"Some files are missing. Your Windows installation or recovery media will provide these files."

I Didn't receive the disks when I received my laptop. I bought it from a Rent to own place, but I did buy it brand new in box and the box was sealed. They informed me if the Cd's were not in there I was out of luck. I was wondering if there was a way to reset the computer without having to purchase the Cd's. I of course over paid at the time of purchase, but I'm a college student on a very low budge and was in desperate need of a laptop. Sadly now my laptop is lagging and I have no way to reboot it.

-Thank you in advance!