Problem description:
Missing drive letter is a relatively common data recovery case, you need to pay attention, do not rebuild a new partition after the drive letter is missing. How to recover the lost data of the drive letter. See the text for the specific recovery method. 
Tools/Software: Extreme Data Recovery Software
Step 1: After opening the extreme data recovery software, directly double-click the disk that needs to be recovered in the software (because the partition is lost, the expression in the software is "free space", where you find the free space as large as the lost partition is needed to restore The disk is now.) 
Step 2: Wait for the program scan to complete, it takes about a few minutes to half an hour, just wait patiently. 
Step 3: Select all files that need to be restored, right-click and select "Copy Selected Files", the program will copy the selected files. 
Step 4: The last step is to wait for the software to COPY the file. 
Note 1: If you want to restore the drive letter by mistake, you need to pay attention. Before data recovery, do not rebuild a new partition.
Note 2: The data recovered by accidentally deleting the drive letter needs to be temporarily saved to other disks.