Why is my USB Flash Drive Now Read-Only?

Open cmd.exe as administrator. Then run the following commands:

1. Type in diskpart.exe and press enter. This will open command line based disk management utility, indicator will change to DISKPART>
2. Within diskpart, type list disk and press enter. This will show all connected disks. Notice the "Size" column and make a note of the disk # you are concerned with.
3. Now type select disk X where X is the numerical digit from step 2.
4. To see its attributes, type attributes disk and press enter.
5. Now that we've ensured it is indeed a read-only disk, we will need to clear the flag. Simply type attributes disk clear readonly and press enter. This should clear the read-only flag.

Now you can format using diskpart or use Windows explorer to manage it.

The drive is going bad. I've seen this happen to USB flash drives before - they are only temporarily good for storage, and you have to keep them backed up.

To confirm that the drive is bad, whilst copying files from the drive I see that it says certain files that are queued for copying do not exist.

Also, it is marked with write-protection, even though there are no registry entries causing that to be so.

A DOS prompt cannot be had!

Trying to copy files from the drive is nearly impossible.

Time to buy a new flash drive.