Appealing PIP?

Hi I am wondering if anybody can help me please I am appealing my award of pip this has been going on for over a year and after 3 requests for 2 of my pip questionnaires the dwp have now said to the tribunal  that they assume they have been dropped from there system or have been deleted in error but they have been able to retrieve the reasoning for there decision please can somebody help me is this normal for the DWP to do and what will the tribunal judge do I appreciate any help you can give me thanks jana