It looks like your stud broke off, you will need to use a tool to drill in the center off the stud and then use a easy out to remove it , If you arent good with these types of tools, take it to the shop or a friend help , you dont want to mess up your head $$$$
http://www.ebay.com/itm/Jims-1705-Ex...VVuRlu&vxp=mtr