How can I find all files downloaded on my computer from the beginning of time, as I want to delete them permanently. I am operating windows 8.1 . All files have been downloaded using google chrome. Thanks
Unless you know where they were download to, you can't.
The normal download folder is \Users\yourusername\Download. You could start there and delete all the files in that folder as long as you have not used it to store other files you want to keep.