Lori Ubrisk, I am a bit confused by your question. You said that is "says my operating system is not found" which would be a hard drive issue, but then you say that your screen stays black and does not display anything. that is a GPU issue for which this model is well know for. Sometimes a reball can fix it, other times you may need a new logic board. Here is my answer to a will not power on :" This is a well documented prob with this series of notebooks and if you do a search on the Internet you'll find lots and lots of unhappy and frustrated people. The problem is the motherboard, and the symptoms include loss of bootup, VERY slow bootup, WiFi stops working, etc. is simply that the MOBO board overheats and fries the video driver chip. The cooling design of this PC is inadequate.
You might try this to verify.
1. Attach an external monitor, see if that shows anything.
If not then:
1. Take the battery out and unplug the charger
2. With the computer lights OFF, press and hold down the power button for 15 seconds
3. Plug the charger back in and start-up the computer
Let us know what you find.