Windows 7 home prem oa

Hello world can some one please help me with a small problem with my dell laptop. 

I have resonantly got a new HDD for which the one i had broke on me and had no recoverable data on it the thing is this os is not easy to get it is a windows 7 home prem oa and I can not find a link for it and the funny thing is I have the product KEY for it how do i find a link please some one help me its been almost half  a year since i use my computer with my new HDD its went to waste DELL does not care. sorry about grammer