If your external hard drive keeps asking you to format it after you have tried all kinds of solutions, you can download free MiniTool Power Data Recovery which is an excellent program that brings file recovery to Windows to have a try. Follow these steps to carry out data recovery process from not formatted external hard drive:
Step 1. Launch MiniTool Power Data Recovery, and then select "Damaged Partition Recovery". You can see this module is specially designed for recovering data from damaged, RAW, or formatted partition when moving mouse over it. So it is most suitable for not formatted hard drive data recovery.
Step 2. Then select the external hard drive to have a full scan (We take a 16 GB Kinston flash drive for example here). The scanning time depends on the capacity of your data in it.
Step 3. When the scanning is finished, Power Data Recovery will show you the files it has found in the hard drive in tree structure. Tick the files and click "Preview" to check whether the files are the right ones. Note: you can press "Filter" button to choose specific file types to be shown in the middle pane.
Step 4. In this step you are expected to click "Save" and then choose a safe location (usually it is another hard drive) to store all data you have selected. After that, wait for the success. https://www.powerdatarecovery.com/hard-drive-recovery/external-hard-drive-needs-formatting.html