Problem description:
Reinstalling the system partition and merging is due to the selection of the wrong option when installing the system, which causes the entire hard disk to be installed as a C drive, and naturally only one disk remains after the installation. After reinstalling the win7 system, the all-in-one machine becomes the C drive and how to recover the data of other drives. See the following for the specific recovery method. 
Tools/Software: Extreme Data Recovery Software
Step 1: After downloading and decompressing the program and running, directly double-click the disk that needs to be restored. 
Step 2: Wait for the software scan to complete and it takes about a few minutes to half an hour. Just wait patiently. 
Step 3: The software will quickly find the information, and the software will list the found disks. 
Step 4: Select all the data to be restored, right-click and select "Copy selected files", the software will copy the checked files. 
Step 5: The last step is to wait for the program to copy the files. 
Note 1: 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.
Note 2: The data recovered by reinstalling the system partition and combining it needs to be temporarily saved to other disks.