Borrow a CD of your computer's system, of have someone reformat it and to make a cd of the system to have in the future. If you have the athondication key code, you can have a cd made, and offer to pay for it, it should not cost you much.
That is so that you can reformat next time you get problems, as they charge a lot to do it professionaly, it it happens often as it does with me.
Most times, it is a hicap which you may need to reformat to get rid of.
It is hard to know what the problem is unless you have the computer in front of you and try a number of different things.
I hope you have fixed it by now.