My iphone showing timer of 3 hour but after 1 hour i check it is same what should i do and also i restart my phone but it cant work

I fall sleep on my iPhone in morning I saw the timer of 3 hour to re enter my pass code after 1.5 hour I rechecked my iPhone the timer is still on 2 hour 56 minutes I re start my iPhone so the erase data option is removed and again the timer start from 3 hour again stop on 2 hour 57 minutes so what should I do ?