Google Search:https://www.google.com/search?client=opera&q=admin+username+and+pass&sourceid=opera&ie=UTF-8&oe=UTF-8#q=inurl:/backup+intitle:index+of+backup+intext:*sql&start=70
1)Find the Back Up
2)Downlod it
3)Import it into phpmyadmin
4)Find the admin username and password :)
Dork submitted by The Vi9er
Good Luck