Sony Xperia C stuck at SONY boot logo - can't turn OFF or reboot

Sir I need help to fix my problem which is a very serious problem as I think my sony xperia c phone is not starting. It is only stuck at boot logo. All it showing is SONY and then nothing else. I can't reset it because I can't remove battery in this phone which is a fixed battery. So problem with my phone is not resolving. Is my phone dead or I can fix it myself. ? Also I don't want to loose my data if factory reset is used on this phone. I have no idea how to fix it and make it work . please help.

I think this phone is stuck into boot loop. Have you tried installing anything which affects phone internally like tried rooting your phone or tried installing something manually , ie. not from Play store ?

Do you have any recovery installed like CWM or TWRP ? If yes then all you need to do is to restore previous backup by booting into it.

But I suspect you don't have those installed otherwise you would not be asking such question here. In that case you have to flash your phone , there are many and one from Sony also.

Flash tool for Xperia
But unfortunately above one is not for your phone ie. Xperia C .

In that you can use either SP Flash tools

or

Perfect Brush

Please search in google or yahoo for detailed instructions.