Hey there, vaughan1.
Sorry to hear about the troubles you're having with the HDD. Just a piece of advice for future references - always keep a backup of your valuable data and in case you don't have one, backup everything at the first sign of any drive issues. Also when your hard drive runs into trouble, you should never run any scans or diagnostic tools before you recover your data. This is because depending on the issue, it could cause the HDD to fail even quicker and it's best to use that time for data recovery instead of scanning.
@ffg7 has a lot of good suggestions for data recovery software, so you can go ahead and try them out. Another option would be to try and access the drive via Ubuntu Live USB/DVD, to see if it's properly recognized and if you can access your data and recover it. The best and most reliable option remains a professional data recovery company, so you can check out this link as well: WD Data Recovery Partners
Please let me know how everything goes.