Battlefield Vietnam

[anarchy]

This might be off topic but i need help.
a while ago i installed a backup version of bfv but one of the discs didn't work so i had to uninstall manually.
the problem is i have now bought the game and tried to install, but the pc still thinks the game is on already.
i have done a search for anything to do with bfv on my hd and deleted whatever was found.
i have also used ashampoo suite and removed any redundant files and cleaned the registry.
the game still wont install.
a friend at work said it could be a dll file in the registry that needs removing but there are 1000's on my hd. how do i know which one to delete, is there an easy way of sorting this problem?