Operating System Not Found

[wiiteen15]

So, I got a used laptop about a month ago. It was working fine until today. I opened it and the laptop started beeping and the Dell loading screen took a bit longer than it usually would. Then, I got this message.
(Check cable connection! PXE-MOF: Exiting Intel PXE ROM. Operating System not found)
Haven't gotten past that screen and it isn't working properly. Does anybody have any ideas on how to fix it?
(My laptop is a Dell Inspiron N7010 and it's running on Windows 10.)

 

[cluedude2210]

Easy fix: Could be you accidentally bumped your computer and your drive somehow got unplugged and you’ll just have to unscrew the back and fix it. Uh oh: you could have lost your entire OS if your hard drive is operating normally. (I know that feel). And you’ll need to reinstall your OS