U Disk Repair Tool has many, the following for you to introduce one of the Portfree Production Progra.
Portfree Production Program is a free U-disk repair tool.
Please click "Options" in the lower right corner of the software.
Second, then select "Other", select "type"--> "Removable device"
Then select "Capacity Correction", where you choose the capacity of your USB flash drive; If you don't have the capacity you want here, click "Add" to fill in the capacity you need.
Third, select "Flash Test", select "low-level format"; Here are two parameters, one is all modules (it means low format of the entire disk), and the other is the normal module (it means only low-format good chunks, this parameter is suitable for the memory stick containing the bad zone).
Four, according to the above method selection, please click "OK", save the settings, and then connect the USB drive to the computer, click "RUN" to start low format.
In addition: if the above method or not, then try the following settings.
If you remember the Vendor string (manufacturer name) and product string for the USB flash drive, change the value here, and then click Run to start the low format.
Note: This value is used to connect the USB stick to the computer before it is displayed. such as: Inserted on the computer is displayed Newman USB Flash Disk