Windows 8 Windows 8.1 won't allow me to delete files in Download folder or run applications. Help!

I have downloaded some applications, and it won't allow me to delete them (it keeps saying the file is open in that application--I checked task manager, and there's nothing there). I read that a program called Unlocker can help, but when I try to run the setup, nothing happens. This is happening for all applications in my Download folder.