I loss all my extension in my windows xp

anybody plss?? who can suggest me what to do. i accidentally deleted all my registry.. now i cant open any application .. i tried to download .reg .inf .zip .exe .msi ,, which I think that could recover all my extension. but it was not.. ..... What Should i do?... when i open my downloaded .reg .inf .zip .exe .msi,, it said "this file does not have a program associated with it peformng this action. create an association i the folder option contrl panel" help me :) thank you.