Samsung S3 I535PP STK.APK **** up.......help!

Well here is a story, one night im sitting here playing with ROM toolbox and i see a app called SIM toolkit. So i think, hey this look cool it might change something on my sim card so im not a prepaid phone anymore......yeahhhhh. I being the dumb-ass that i am tap it and try to turn it into a user app. now the Toolkit app disappeared and now my system ui crashes and i have no home-screen. I have a Samsung Galaxy S3 I535PP.....any help is a blessing :)!