Fsx Product Key Urgent...about Product Key...plz Help.....FSX?

Urgent...about product key...plz help.....FSX? - fsx product key

I installed FSX on my PC and I have also inserted the product key and your good game ... I can not play multiplayer mode .. lasts but after a few days, my computer does not work, then ..... Formatting my computer and changed the hard drive .... and now I have installed FSX and there is no crack file (product key ).... What should I do?