So my problem is the following:

I had a 1 TB Seagate disk with two partitions, one was for data ( ~ 629 GB ) and the other had a Windows 10 installation ( ~ 300 GB ). Then what I did was deleting the Windows 10 partition/volume and also the reserved Windows 10 volumes/partitions ( I had installed windows on another disk so I didn't need it anymore ).

After that, I had extended the data partition with disk management using the unallocated space of the old Windows 10 partition. Windows asked me to convert the disk into a dynamic one and I accepted.So I was seeing two volumes on disk management which were shown as one disk on File Explorer and they were working fine. Don't ask me why I deleted the ex-Windows 10 partition and what happened is that both partition got deleted and now I was seeing 1 TB ( 931 GB to be specific ) of unallocated space. I created a new disk without formatting and now I see an inaccessible RAW data disk.

What I want to do is recover/restore the original ~ 629 GB partition I don't care about the old Windows 10 partition. I'm trying to use DMDE but I'm not sure what to do, I can provide more screenshots if needed.

Sir ,
What Model HDD is This exact model please ,check in some utility

_________________
Regards
Amarbir S Dhillon , Chandigarh Data Recovery Labs [India]
Logical,Semi Physical And Physical Data Recovery
Website-> http://www.chandigarhdatarecovery.com

It's in the screenshot ST10000DM10 so should be CMR.

Your files should be visible if you select the 676GB partition - you should be able to recover from there, I don't like in situ partition restoration.

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Data Recovery Services in the UK.
https://www.usbrecovery.co.uk/

Yes they are but I would like to restore somehow the partition, I don't have an external free drive.

Just select Disk 1 - right click - GPT off - right click 676 GB partition and select restore boot sector from copy - right click on the same partition and select insert the partition - power off and power on the drive.
Now you have full access to your deleted partition and unallocated 300GB.

Sorry ,
I missed that ,this should be recoverable .

_________________
Regards
Amarbir S Dhillon , Chandigarh Data Recovery Labs [India]
Logical,Semi Physical And Physical Data Recovery
Website-> http://www.chandigarhdatarecovery.com