what do I do with these invoice?

Hello Team, 

I am holding a wholesale tire shop, and during the summertime, I had three deliveries to the same customers, the total value is 4500 dollars. But I received two post cheques and the third payment is unpaid from the beginning and the two cheques were bounced back from the bank. 

when I received the letter from the bank, and I tried to contact the owner. I got the news from their neighbour that their business owner ran away, and the business shut down. so I lost the items that I delivered, and 4500 dollars unpaid invoice still in the QuickBooks. 

questions,

1 what do I do with these invoices before the tax season?

2 Tires are not  breakable items, so those tires that I lost, WHAT should I do with inventory?

Thanks