mobile

Hello Guys. I want to ask how to reroot my galaxy core 2 bcos i lost root access.
i use kinguser to root my device. Then the applicatoon is installed on my sd card. But my sd card wont workanymore. I try reroot again using kinguser. But when i check using root checker it says "root not properly installed". The apk of kinguser dnt already appear on the screen. What should i do??