Please make sure that you pendrive is not write protected, refer to the link below:
You can try to using a tool like HP format tool. here is the link:
If this solution does not work, follow these steps:
1-Click on Start
2-Right click on my computer
3-Click on manage then click on storage
4-Click on disk management
5-Right click on your device and select add letters and path, a window will pop up then click on Add then select an alphabet different of C and click on Ok.
If the solutions above don't work, that mean your drive is certainly corrupted and it can't be repaired. Think to a buy a new one.