Then I tried looking into apps space and every other place but couldn't find where the damn obb file went and yet space was full. I tried deleting obb folder but it kept saying operation failed. My data was taking up only 1 mb of all storage space.
Finally, in the end I had to factory reset and then the storage became normal once again.
So can anybody tell me what might be the cause of it? Only 2 apps were installed- Superbeam and Asphalt 8.
Also, anyway not to reproduce this problem again?