Iphone 5S Clock problem on ios 8.1.2

Hi,

I have big problem with my iphone.

When i install ios 8,1,2 on my phone the clock stop.

I lock phone in 12:00h and i unlock him on 13:00 clock are freeze on 12:00h.

What can i do now to clock are work?i reinstall the software and master reset phone and is still freeze.

Sory my english is bad 🙂

Please help me!

Enything on phone woork nice only the clock are freeze 😟