Hard drive not installed and system restore point

Hello,
Last night my computer began acting weird so I restarted it. When I did that, it went to support assist and it said hard drive not installed. I have had this happen in another computer and I did was a system restore from the last point that it was working. I tried the whole F8 thing and it wont even go to the options for that. Now it just keeps saying the hard drive not installed and preparing automatic repair. What do I do? How do I fix the problems without losing everything on it?