Missing Theme

Hi all,
I have installed my wordpress website and used the theme 2012 ,I did change the theme a few times and decided 2012 was fine …It say’s I have 2012 installed , however it does not show at all ..When I view the page or preview in the dashboard …I added the title of the website so maybe I made a dog’s breakfast of it ?…Would appreciate any advice , I would uninstall if I knew how …the only thing I hate getting into deleting files etc …Many thanks…