Thanks for your reply.
I tried to restore using recovery mode it give error 4013, also tried the same with iMac with my friend again error.
Let me give little more details:
1. After iOS 8.2 upgrade, 2-3 days often 3-4 times a day it used to restart again and again then will get Home screen.
2. Also at times it happened, it boots again and again left the device as it is then it comes to Home screen.
3. Lastly it did the same behavior but it did not boot up, but keep booting again and again apple logo is shown then restart
4. Tried to get into recovery mode, windows PC error 4013, now in the recovery mode.
My Battery was in good condition, when it happened it was ~80% now may be very less did not charge until now.
I read somewhere in the forum keep re-starting manually again and again, someone said since it did not shutdown properly there is a problem, please help.
The device is 1.2 yrs old ONLY.
Best regards
Prabu