Finally we found the solution for Ovi Store problem which we posted over here.

Case 1
1. If you have done a hard reset and Ovi Store Stopped working then you just have to flash your Nokia N8 with Phoenix with default Firmware.

How to Flash Hacked Firmware on Nokia N8 with Phoenix? Click here

Case 2
Just re-install the Symbian Belle firmware via Nokia Suite and all Qt issues will be fixed.