So, you are trying to recover data from the missing partitions? Any idea why Disk Utility would not repair? Is it formatted HFS+? If it is NTFS with the WD software tool to make it read/writeable to a Mac, then that would explain why DU will not work.
FYI: It is best to format new drives for Macs. Several of the big brands include software tools that allow using NTFS drives on Macs, but is messy and can be frustrating to move the drive between multiple Macs.
The recovery tool(s) will vary depending on the format.
For HFS+: Back in the day...I would say start with Disk Warrior, but it seems like a dead-end product since the advent of APFS. As an external Mac drive is likely to
not be APFS, it might still be worth trying, though it is pricey to find out at $120 for HFS+ issues.
I have had decent luck with Drive Drill Pro and Data Resue, mostly on flash drives for photography or older hard drives. Free to see what it can recover, costs to restore data. Most of the known tools are written up in
this review.