Touch ID does not work on my iphone6

Suddenly my touch ID does not work & i think its disabled and i cant access Settings > Touch ID & Passcode > enter my passcode > iPhone unlock. when i touch it to "ON" its says "Failed, unable to complete Touch ID setup. please go back and try again" is that a version(8.3) problem or hardware failure. i reset my phone, restart many times, did soft reset, hard reset, restore phone setup and all that thing but doesn't work. what can i do now? please suggest me.

I bought my iphone 6 from USA around 6 month ago, now using it in Bangladesh. still have 6 month warranty.

"Shemon"