Cannot Install theme

I have tried multiple methods as listed on the support threads within this support site. I tried doing it through FTP as well as through the back-end wp-admin. However at first I was getting the “Are you sure you want to do this? Please try again” error. When I tried FTP I finally got it installed, but when I clicked to apply the theme everything went white. When I went to my website URL it went white and would display nothing and I could no longer access my Wp-Admin either. Since then I installed a fresh WordPress 3.9.1 and am waiting for a reply with help for this issue.