How do you upload a Backup Folder?

I completely ruined my site somehow and am very confused as to how I can restore it to its proper form.

My question is: How can I restore my original site using the original folder (“https://—.com/test3”) as my source? I also have a SQL file (though not sure how to use that either!).

More info:
I messed up my website because I changed the URL in the General Settings to a completely different website, and then I was unable to access my admin panel to change it back. I think my techniques of trying to fix it only made it worse (deleting the files and uploading the backup files).