Salvaging data from hard drive

Pull the hard drive from the laptop and check the connectors to make sure they are clean and not corroded. If there is corrosion on the connectors or the board on the bottom of the drive, it may need to first be cleaned. Use a USB to SATA Adapter/dock/enclosure and connect the drive to another Mac. If the drive is functional you should be able to mount and unlock the drive to transfer your files. You may need to use Disk Utility to mount the drive as macOS does not always prompt the user to unlock Filevault when connecting a drive externally.

If this does not work, then you will need to use a professional data recovery service such as Drive Savers or Kroll OnTrack. Both are recommended by Apple and other major OEMs and both provide free estimates. We used Drive Savers several times many years ago and we were quite satisfied with them.

All you can do is try—

commercial software DataRescue5 https://www.prosofteng.com/mac-data-recovery/

Ontrack data a Professional Data Recovery Service

Ontrack quoted USD500 to save my data.

https://www.ontrack.com/