Why have the faxes I sent from my developers phone number been deleted?

I have an application that has been moved to production, but I was creating a second application that was looking at the faxes sent from my development number. I had faxes in there last week but when I checked today, they appear to be all gone and when I have swung the app back to sandbox settings, it is not sending the faxes out - they are stuck in the outbox. Can you restore the faxes that were in there, or advise me how to add new ones to the sandbox number - the number is 14243302364