Spent all day for this. Please help

I erased everything on my mac and reinstalled.
Then I connected my hard drive, but nothing showed up.
I downloaded utilities and stuff from WD website but nothing happened.
I read some articles and was trying solutions.
I accidentally formatted it by using Partition in Disk Utility.
Luckily my storage still says I have 2 TB left out of 4TB (so I assume my files are still in there).
BUT I still don’t see my files yet now I see the partitioned portion only.

If anyone knows how to fix this, please let me know. Thanks.

Which macOS version are you running? and what is the file system you used?