Unallocated Drive but don't want to lose the data

After windows 10 last update my windows was corrupted and I could not find a fix. After hours of research and trying to find a way to fix my problem I decided reinstalling windows was the way to go.

I have two internal drives. Drive C and Drive D. My drive C works fine and all my window problems were fixed. But now I don't see my drive D even though it is there. When I ran windows Disk Management it shows the drive but it is unallocated.

My drive D is loaded with data that I don't want to lose. When searching for a solution, ever solution was an ad for buying software to fix the problem. If that is what I have to do I will but before I take another step I wanted to get feedback. Maybe if I would of done that in the first place I would not be having this problem.

So the question is. How do I fix my unallocated internal Drive D without losing the data on it.

Thanks

p.s. I'm using windows 10

Your specs show only 1 hard drive.

You say "I have 2 internal hard drives. Drive C and Drive D".

Clarify: are C and D different partitions on the same Samsung 860 Evo or are they two separate and discrete hard drives??

If they are 2 separate and discrete hard drives, did you disconnect D before re-installing Windows to C??

A screen shot of Windows Disk Management might help.

If D is in fact unallocated, your only choice may be to use partition recovery software and hope for the best.

Member Jumanji is probably the best here to help you with that if you need data or partition recovery help.

Hello,
You may try fixing your partition by using this command (open cmd or powershell as administrator):
chkdsk D: /X /F /R

*assuming that partition D: is mounted but not accessible, other wise you may not run this command as it may check and fix another partition which is mounted in D: drive letter instead of the lost one,
in this case you might need a recovery program like: partition find and mount.
But I'll search for another excellent app and share it's name or the portable version if I find it

- - - Updated - - -

here it is,
It's a very old version that I found it in Hiren Boot CD version 15.2, but it still does the job.


- - - Updated - - -

I've extracted and uploaded the version I got from Hiren Boot CD 15.2, and a screenshot is included in the compressed folder