Widh
You don't say what is happening with your appeal?
There is no reason why an appeal cannot still be carried out although the TS may require you re-submit it if they cannot find the original papers. If they do, then you should remind them that they lost the original papers in you reasons for the request being late.
You can also make a new claim for PIP, assessment time are down but it is still taking long than 26 weeks in most regions of the country for a Decision to be made. You need to be aware that any Decision that results from your making another claim will limit any Decision that might result from an appeal of the original Decision.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems