I have a HUGE computer problem!! Please help?

I purchased MS Office Pro (student version) from the university I attend and have a valid product key (according to MS tech support), but after having some computer problems and using the restore feature which reconfigured my computer to factory condition, I can't get Office Starter to take the key, and it says I don't have a valid key. Help, I have spent hours and hours on this and I am reading to throw this stupid computer into the trash and the computer is less than 6 months old!!