Problem description:
Reinstalling the system partition and merging is because when the system was reinstalled, the wrong option was selected, which caused the entire hard disk to be installed as the C drive. After the installation, naturally only the C drive is left. After the ghost system, there is only one disk and how to retrieve the files on other disks. For the specific recovery method, see below. 
Tools/Software: Extreme Data Recovery Software
Step 1: After Baidu search and download the program to run, directly double-click the partition to be restored. 
Step 2: It usually takes a few minutes to half an hour to wait for the program to scan. 
Step 3: After the software finds the data, the software will list the found disks. 
Step 4: Select the file you want to restore, right-click and select "Copy Selected File", the program will COPY the checked file. 
Step 5: The last step only needs to wait for the program to copy the data. 
Note 1: The data recovered by reinstalling the system partition and combining it needs to be temporarily saved to other disks.
Note 2: If you want to restore the reinstallation of the system partition and merge, you need to pay attention, before the data is restored, do not save new files to the C drive.