Unhappy [Q] galaxy s3 (root) freeze and reboots

i rooted galaxy s3 4.1.2
everything worked fine for 2 days
but now every app freezes and phone reboots
i can jst acsess system setting and make calls
if i open any app it freezes and system reboots
i can not even unroot because "triangle away"also freezes and my binary count is 1
this happen when app requests root permission to super user ...SU always denies it and app freezes