Access filesystem of Nokia 920 to get WhatsApp database

Good evening,

I am using my windows nokia 920 with windows mobile 8.1. I would to get access to my whatsapp database to make an backof of outside my Phone. Because the 920 has no SD Card slot, i can not create a backup on it.

So I am looking for an App that can backup the database to an external location, or have full access to my windows Phone directory. Please help me...

Thanks so much