Endless apple logo after iOS 9.1 update iPhone 6

3 Day before I switched-on my iPhone 6 (running 8.x) I have faced following issues

• I mentioned it was running very slow, immediately I noticed on date which was changed 1 January 1970.
• When I tried to tap on setting icon to change the date it take more than 15 second to open and immediately returned back to home screen, several times I tried but nothing work to change date.
• I have restarted my iPhone 6 again which was locked with passcode when I tap on key it respond very slow.
• iPhone started and working very much slow.
• I connect my iPhone to iTunes and updated to iOS 9.1 update.
• Update process was completed and i read message in iTunes"waiting from iPhone" I found Apple logo with empty progress bar.

I tried several times to reboot my phone but Apple logo appears and never goes.

Please, please help me in this situation. I don't want Android user to abuse me and force to use Android rather than Apple. I really love iOS devices.

Thanks