Some time back what happened to me that one of my pen drive denied any access to write any file over it though i can access files stored. Actually this problem start when I used it on one of my friends PC and it got infected by any virus. Even several attempts to reformatting was also not giving me any result. Even i have tried it use it on several pc’s but a waste effort. So what to do? It was not an advisable idea to leave it as it is…. But finally I made it to work … know how?

Step One: First to find whether it is blocked with in the registry or not.. To Check open registry editor using Windows+r key and then typing Regedit in the run window. After getting the registry editor opened, navigate to the key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\ and then look for subkey inside it named “StorageDevicePolicies”. If it does not exist there then it is ok pen drive or removable is not blocked with in the registry.

More Info: You can always block a removable media on your own wish to do so in the key you have searched above Right click on “Control” key -> New -> Key. Name it “StorageDevicePolicies” without quotes. Now right click on this newly created key and then click New -> DWORD value and name it as “WriteProtect”. Now double click over the newly created Dword value and change its value to 1 and click ok. Once you restart it on this PC you can not write any content to removable disk.

So now move on what if that sub key StorageDevicePolicies exist then to remove it just change the dword value to 0 and registry modification are complete.

Now check once again if you could write or delete files from a pen drive or not. If not then proceed to next step.

Step Two: If the above step has not yielded any result then there may be the chances that there may be a file infected by a virus which has locked it an you may need to have an Unlocker Utility which is well capable of killing the application using such file. And for this purpose I have found the best utility Unlocker (You can find a review here) Just download this application from the link given below and install it. This is what which has worked for me and hopefully it may also solve your problem.

Download Unlocker latest version

Once downloaded install it and now from Right Click over any file that you want to delete, choose UNLOCKER it will then show which are the application blocking that particular file and there you can kill or unblock the application or file and then you can use HP format Disk utility to format the removable disk. This may probably fix your problem.

If again the problem occurs you may try Formatting by Dos from the following Article

Formatting an Unformattable Pen Drive… A simple DOS Command