Hello, i have a problem and maybe you could help me...

Few years ago i had a wallet on multibit in my macbook. There is no passcode i open it the software and use it. Every month i sended BTC in my wallet but one day .. i send it at the same BTC adresse but when i open Multibit the adresse had change and i lost my fund because i didn't take the private key before.
I have the folder with wallet.dat , peers.dat , etc...
I try pywallet but there nothing detected...
Can you help me?