just put in the install disc for windows and try that
Well you need to tell him more than "put it in" or he might not know what to do afterwards.
And don't do an install or you might lose stuff
run startup repair
stuff where do I find that
Wherever you put it? We can't answer that lol
Unless it's a prebuilt from a brand that doesn't give you the disc (+1 reason not to buy prebuilt)
If you have access to another computer with the same os, Google "<your os version> create repair disc"