trying to re-establish xampp


Hi, a little help please, I'm running window7 and trying to re-establish xampp.
I had a working version but in trying to run PDO found that I needed to up above 7.
I uninstalled and now this...
I'm told I have antivirus running running although I only know of windows defender.
I've tried to change uac settings, probably erroneously. Anyway I tried to just
try anyway. when offered "C:\xampp" I click next and am told "not empty, select
different folder". What must I do? Thanks guys.