Microsoft office home and student 2010 help?

I have the product key but I think the disk is corrupt so I am not able to use autorum and activate from ten disk. I know there is a link that microsoft has where I can directly enter the product key and validate it and have the program installed. I had to clean my hard drive recently and had saved the link but I cannot remember what it is now. If anyone knows how to get to this link I would be grateful