Data Recovery

I would start by using both the Disk Utility's First Aid feature and the DriveDX app to determine if this drive is readable.

• If it is, then you can attempt to recover data yourself, using an app, like DiskDrill.
• If it is not, then you will need to employ the service of an outfit that specializes in data recovery. Be prepared for two things: 1) The service can be expensive, and 2) There's no guarantee that can recover all or any of the data.

Sorry, that didn't work out. Best of luck with the data recovery folks.

A bit late, but you may want to update your backup strategy, especially if data is critical to you. I wrote this user tip on that topic. Hopefully, it will give you some ideas that will help you prevent this in the future. All I know is that I have been using computers for a number of decades now and I have yet to have a data loss that I wasn't able to recover from.

Ref: macOS Backup Strategy - Apple Community