How do I recover funds for repairs made to a property I intended to buy if the contract is declared null and void by the sellers attorney?

That's a tough one.   Why would you make repairs to the property without some kind of agreement as to what would happen if the deal fell through?  The seller just declared the contract void?  You are going to be bound by the terms of the contract, and if the contract allowed you to do repairs and then provided some reimbursement if the deal fell through, that's what you'll be stuck with,  If there was nothing in the contract, then your remedy is for breach of the contract if the seller's attorney did not have a legitimate reason to void the contract.