iPhone 6s all data lost while updating to ios11

While my iPhone 6s was getting updated to ios 11, it got switched off between.

And then when I switched my phone On after sometime, it started as a brand new phone.

I believe, my phone got automatically reset to factory settings.

So my all data got lost, and I dont have any recent backup to iCloud or iTunes.

Please suggest, is there any other way I can get my data back?