How to Recover Lost Space on a USB Drive
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I play around a lot with my USB flash drives. They’re useful for so many things beyond just transferring files between devices. For example, you can use a USB drive to lock and unlock your computer as well as carry around portable apps everywhere you go Are USB Flash Drives Still Worth It In 2015? Are USB Flash Drives Still Worth It In 2015? USB flash drives are great for storage, but they have so many other uses. Here's how they're worth their weight in gold. Read More .

As for me, I mostly use them as bootable drives for ISO files 10 Tools to Make a Bootable USB From an ISO File 10 Tools to Make a Bootable USB From an ISO File Installing an operating system from a USB drive is quick and portable. We test a few ISO to USB tools to find the best one for you. Read More , which comes in handy when I want to try new flavors of Linux or turn a bricked laptop back into a Windows machine.

But I recently ran into a weird problem: I’m not sure how, but my 4 GB USB drive was suddenly showing up as a 100 MB USB drive. I’d lost a huge chunk of my drive’s storage capacity! Fortunately I found a fix, and if this has happened to you, rest assured that the fix is surprisingly simple.

As it turns out, the USB drive’s partitions had been tampered with, leaving most of the drive “unallocated” and inaccessible. That’s likely what happened to your drive. To fix this, we’ll just reset the partitions on the drive and “reallocate” all of the space as a new, single partition.

How to Recover Lost Space on a USB Drive diskpart reset partition usb drive

Before going ahead, back up your data! The following steps will completely wipe your drive. And make sure you pay attention to step 4 as you don’t want to accidentally wipe the wrong one!

  1. In the Start Menu, search for and launch diskpart.
  2. Type list disk to see all current disk volumes on your system.
  3. Plug in your USB drive and type list disk again. Note the newly listed volume.
  4. Type select disk # where # corresponds to your USB drive’s volume number.
  5. Type clean to wipe the volume of all partitions.
  6. Type create partition primary to make a new partition with all unallocated space.
  7. Type exit to finish.

If done correctly, your USB drive should be back to normal: a single partition with all of the space on the drive properly allocated and used. No more lost space!

What do you use your USB drives for? How did your drive lose its space, anyway? Share with us in the comments below!

Explore more about: Troubleshooting, USB Drive, Windows Tricks.

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  1. John Smith
    November 11, 2018 at 8:34 am

    Thank you for posting this.

    It was easy to follow and worked perfectly.

  2. Kris
    September 9, 2018 at 1:40 pm

    This was a HUGE help. Thank you!

  3. Marcus
    August 28, 2018 at 3:43 pm

    Thanks a lot. Got back 100GB. Saved me a lot of money.

  4. Gaurav Srivastava
    August 8, 2018 at 3:59 pm

    It worked well, I have gained all the space 14.5 GB in 16 GB drive. Thanks.

  5. Anandh Jose
    July 19, 2018 at 5:09 pm

    Saved my day. Thanks a ton!

  6. Aadil
    January 11, 2018 at 5:13 pm

    it worked for really 4 gb usb drive showed unallocated space, i tried so many methods but nothing worked.i tried the above method & it worked.thanks a lot

  7. Anbarasan Devadass
    March 13, 2017 at 5:26 am

    Whenever I make Ubuntu 14 bootable USB my 16GB drive shrinked to 2MB. I use HPFormattingTool in windows to recover.

  8. William Vasquez
    March 10, 2017 at 5:03 pm

    You should also add this line at the end before 'exit'.
    format fs=Fat32
    This makes sure it is formatted to use right away.

  9. pajades
    March 9, 2017 at 7:37 pm

    COOL! I've had this "protected" 4GB USBdrive sitting on my desk at work for the past couple of years - numerous attempts to wipe it for reuse have failed... Until now! I now have an extra (usable) 4GB USB drive. Thanks!

  10. Tony
    March 9, 2017 at 6:16 pm

    You can also do a low level format on your usb stick to free up any space that's not accounted for.

  11. spyjoshx
    March 9, 2017 at 4:09 pm

    You can also do this with graphical tools like Gparted on linux, disk manager on windows, and disk tool on Mac.