You have been incredibly naive - did you really think that you could walk away from a mortgage just by telling the mortgagees that you were no longer living at the mortgaged property and you were "washing your hands" of it?(posted 7534 days ago)The one, perhaps for you, good side of it is his father is guarantor and he is probably in a better position to be forced to pay up on both your behalves - and yes, you can be held responsible for the whole of the debt - known as joint and several liability.
You have 3 choices basically:
1. Do nothing and let the law take its course - if you have no money they can sieze including wages, no effective goods they can take, and no property they can charge over, then they are likely to give up.
2. Offer a payment each month - you dont say what your current circumstances are.
3. Fight back and apply for the court orders to be set aside and reheard with you as a defendant. However, you have to do this within a very short space of time of knowing you have a judgment made against you, and is unlikely to succeed if the judge thinks you have no real prospect of defence.
If you can, get some good legal advice on this with all the facts disclosed (not just what we see here which is obviously condensed) - you may qualify for legal aid even if working - apply and see.