The law and the civil courts are not an always the best remedy, particularly within a family, I have seen families torn apart over what to others appear a minor matter. You should ask yourself what will the other side say, probably that you asked them to help and you did not put a time limit on when the documents should be returned. If you do not think a quiet chat will get your papers returned ask a solicitor to write and demand the return of your documents, with vague talk of legal action if they have not done so within 14 days, (this may not make you flavour of the month).
When dealing with your debts the first stage will be to divide them into priority debts, Council Tax, Fines, Mortgage and anything secured debts and non-priority debts, loans, credit cards, non-secured debts et cetera, there are many organisations that will help.