Hello, I'm so sorry about your experience. The possibility of recovering your data is too small, depending on your hard drive is corrupted by the water.
- Remove all plug-in devices then dry and drain you MacBook.
- Check the hard drive of your Mac. You can check the connectors to make sure they are clean and not corroded. If there are no changes, move to Step 2. If it is watered, please connect to the local professional Apple store and ask for help.
- If there is corrosion on the connectors or the board on the bottom of the drive, it may need to first be cleaned and then use a USB to SATA Adapter/dock/enclosure and connect the drive to another Mac.
(Note: Maybe you will mount and unlock the drive to transfer your files.) - Use Disk Utility to mount the drive. You can use First Aid to repair it.
- If Step 3 and Step 4 don't work, then you will need to use a professional data recovery service such as iBoysoft Data Recovery for Mac, an effective and reliable tool to help you recover all your data.
Hope your hard drive is ok and you can recover all your data finally.