U disk repair tools are many, below 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, select "Other" and select "type"--> "Removable device"
Then choose "Capacity correction", where you choose the capacity of your U disk; If you don't have the capacity you want here, please click "Add" to fill in your desired capacity.
Third, choose "Flash Test", select "low-level format"; Here are two parameters, one for all modules (which means the entire disk is low format), and the other is the normal module (it means a low formatted block, which is suitable for a USB disk with a bad area).
Four, all according to the above method selection, please click "OK", save the settings, and then the U disk to the computer, click "RUN", start the low format.
In addition: If the above method is still not good, then try the following settings.
If you remember the vendor string (manufacturer name) and product string (product name) of the U disk, you change the value here and then click Run to start the low format.
Note: This value is used to access the U disk on the computer will be displayed. such as: Plug in on the computer are displayed Newman USB Flash Disk