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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)

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Tried to remove the files? – Gunnar Hjalmarsson Jul 11 '14 at 5:41
Try to fix it from Windows Disk Management Tool. – Nischay Jul 11 '14 at 5:44

If you want to know how to reformat your 8GB pendrive from Windows 7, then ask how to do it on Superuser Q&A, not here. The following commands are run from the terminal in Ubuntu.

  1. Remove all of your USB devices except for the 8GB USB pendrive that you want to reformat, so you won't get confused about the device name of the USB pendrive later on.

  2. List all the partitions.

    sudo fdisk -l

    Search the results of the command for output that looks like this:

    Disk /dev/sdc: 7864 MB, 7864320000 bytes
    30 heads, 33 sectors/track, 15515 cylinders, total 15360000 sectors
    Units = sectors of 1 * 512 = 512 bytes
    Sector size (logical/physical): 512 bytes / 512 bytes
    I/O size (minimum/optimal): 512 bytes / 512 bytes
    Disk identifier: 0x00016288
       Device Boot      Start         End      Blocks   Id  System
    /dev/sdc1   *        2048    15359999     7678976    b  W95 FAT32

    If you see something like 7864 MB (8GB) in the output (see the example output above), then that is your 8GB USB flash drive. In this example it is called /dev/sdc. Now open the Disks application from the Dash and check again to make sure that the device name of your 8GB pendrive is the same as what you got from running the command: sudo fdisk -l.

  3. Create a partition table on the disk of type msdos, sometimes known as Master Boot Record.

    sudo parted /dev/sdc mklabel msdos

    In this example I used /dev/sdc for the name of the device which is what was found in the results of step 2. I can't stress strongly enough how important it is to verify the device name before running this step!

    Warning: If you type the wrong device name you may overwrite your operating system or another one of your partitions containing important personal files!!! So be careful and check the device name a second time. Open the Disks application and check the device name of your 8GB USB flash drive in Disks. It should be the same device name!!! Now check again! You don't want to accidentally type the wrong device name!

  4. Add an empty "primary" partition, which will hold a FAT filesystem later.

    sudo parted -a none /dev/sdc mkpart primary fat32 0 8192 

    Once again in this example I used /dev/sdc for the name of the device which is what was found in the results of step 2. The command specifies the start point (from 0 MB) to the end point (8192 MB). If the 8GB USB flash drive does not have the full 8192 MB space, parted will adjust it automatically. If the terminal returns a message that the start point can't start at 0 MB and you have to use some other small number close to 0 MB, type Y to accept this. Note the command is creating a single, primary partition on the whole disk.

    This newly created partition will have the ID /dev/sdc1. That is because the device name in this example is /dev/sdc and the 1 at the end is because it is the first partition on that device.

  5. Create a FAT filesystem on the /dev/sdc1 partition by formatting the partition.

    mkfs.vfat -n "8GB-USB" /dev/sdc1

    /dev/sdc1 is the partition ID from step 4. "8GB-USB" is the partition label, which can be your own choice of label, just enclose the label inside two double quote characters.

You now have a ready-to-use reformatted USB flash drive with an 8GB FAT partition.

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You can also/instead suggest to plug the device, do a dmesg and look for USB in last lines. Or dmesg | grep USB. It would be option 2b or something like that. – CijcoSistems Jul 11 '14 at 9:12

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