Windows Vista Operating System Not Found

Help! My Gateway Laptop just suddenly stopped working, whenever I turn it on I get a black screen that says some junk and then Operating System Not Found. I checked to see that the hard drive had not come loose and it hasn't. It also says media test failure, check cable. What should I do?

Do you have an extra hard drive that u can borrow and put in the system to see if it works?

No, have another laptop, its also a Gateway but a couple of years newer. I'm assuming it won't fit.