Hello Vinay
How was your day / night.
Why do you think you need to do a hard reset?
If you need a user manual you can download one from [http://www.airwheel.net/manual/Airwheel_C_series_user_manual.pdf|here].
Airwheel doesn't state how to or if it can be hard resetted.
I would contact Airwheel using [http://www.airwheel.net/home/contactus|this form.]
Hope this helps.
David