I recently made my pen-drive bootable with Ubuntu 14.04. But I need to unboot my pen-drive now. I formatted my pen-drive once,But the size of the pen-drive still shows 2.25 MB. Whereas,this is an 8GB pen-drive. How can I get rid of this problem. Anyone please help! (I'm still using Windows 7)


Start administrator's command prompt:

  • Open start menu
  • Type cmd
  • Press Ctrl+Shift+Enter

Fire up the utility called diskpart. Literally, enter diskpart command.

DISKPART> prompt should appear.

Now in diskpart prompt type: LIST DISK and it will list all your Disks including your USB drive. Note the Disk number.

Type the SELECT DISK <num>, where <num> is your USB disk number. Just look for right capacity of the drive.

List all partitions on it: LIST PARTITION.

For every one of them type: SELECT PARTITION <num>, where <num> is the number of partition and DELETE PARTITION.

Now check there aren't any of partitions left: LIST PARTITION. If there aren't any create one partition:

CREATE PARTITION PRIMARY - If it asks about size, just use the default value - it is the max capacity

FORMAT FS=FAT32 QUICK - I think USB flash drives use FAT32 filesystem by default. You could use NTFS instead too.

That's it!

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  • 3
    Just a small remark: If it’s a thumb drive, you can’t properly manage partitions with Windows. You can, however, delete all of them with the clean command, instead of deleting each partition individually. Just make sure you have the correct disk selected, because there are no safeties. – Daniel B Jan 9 '15 at 14:18
  • For anyone getting the error volume to large, use FORMAT FS=NTFS QUICK. – Martin P. Jul 27 '17 at 11:30

Take a look at "Restore USB Flash Disk Back to Full Capacity": http://www.trishtech.com/2011/06/restore-usb-flash-disk-back-to-full-capacity/

Often malware infects the USB disks in such a way that the capacity of the USB disks is reduced. For example, a 8GB USB flash key may show up only as a 500kb USB key in Windows. Even after you remove the malware or format such a disk, the capacity does not change and you are pretty much stuck. But thanks to a tiny software called BootIce, you can now format such a USB disk and restore them back to their original full capacity.

BootIce is freeware for Windows. The download is in form of an portable EXE file. BootIce is a standalone Windows program so it does not require installation.

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To restore the usb drive you can use the dd utility. You will need a linux environment to run this command. dd count=1 bs=512 if=/dev/zero of=/dev/sdx && sync should do it. Before you proceed with the command read the entire post.

Ok. For the section that says /dev/sdx, the 'x' represents the letter that identifies the device. For example, /dev/sda is usually the name of the first storage device mounted by the system, usually the internal hard-disk. If you have other storage devices connected the 'x' increments in alphabetic order. A simple way to check the name assigned to your usb device is by running the command ls -l /dev/disk/by-id/usb*. This list all the mounted usb devices and their partitions. A partiton is denoted by a number after the letter identifier, eg. /dev/sda1; for the purpose of solving this problem partitions are of no concern to us so disregard the number at the end. Once you have identified the usb device you can run the dd command above.

The dd command is destructive so ensure you type everything correctly. If you have any concerns ask in the comments.

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