If you unchecked "Encrypt wallet file" when creating the wallet, now you can open the wallet file and see your balance, transactions history and addresses, but you will still need the password for making any transaction. Your secrets like your seed phrase are encrypted.
But how did he manage to know the balance? I thought that the seeds and private keys are encrypted using AES-256-CBC, and therefore if you only have the file and without a password, you will not be able to know your balance.
@OP since you did not use any program to generate a strong password, it is probably one of the passwords that you use most often, or at least part of it.
If you can know the length of the password or exclude things that cannot be in that password, then your options will be greatly reduced.
You can contact WalletRecoveryServices
walletrecoveryservices@gmail.com