try to format it using DOS prompt
Start > Run > type 'cmd' without quotes.
In Console write : format [Pen Drive Name]:
Press Enter
Example:
c:/>format H:
Dont Forgot to put : sign after Pen Drive Name.
For More Help on Format Command Read This:
Format
Formats the disk in the specified volume to accept Windows files.
Syntax
format volume [/fs:file-system] [/v:label] [/q] [/a:UnitSize] [/c] [/x]
format volume [/v:label] [/q] [/f:size]
format volume [/v:label] [/q] [/t:tracks /n:sectors]
format volume [/v:label] [/q]
format volume [/q]
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Parameters
volume : Specifies the mount point, volume name, or drive letter of the drive you want to format. If you do not specify any of the following command-line options, format uses the volume type to determine the default format for the disk.
/fs:file-system : Specifies the file system to use FAT, FAT32, or NTFS Floppy disks can use only the FAT file system.
/v:label : Specifies the volume label. If you omit the /v command-line option or use it without specifying a volume label, format prompts you for the volume label after the formatting is completed. Use the syntax /v: to prevent the prompt for a volume label. If you format more than one disk by using one format command, all of the disks will be given the same volume label. For more information about disk volume labels, click Dir, Label, and Vol in the Related Topics list.
/a:UnitSize : Specifies the allocation unit size to use on FAT, FAT32, or NTFS volumes. If you do not specify UnitSize, it is chosen based on volume size. The following table lists valid values for UnitSize.
Value Description
512
Creates 512 bytes per cluster.
1024
Creates 1024 bytes per cluster.
2048
Creates 2048 bytes per cluster.
4096
Creates 4096 bytes per cluster.
8192
Creates 8192 bytes per cluster.
16K
Creates 16 kilobytes per cluster.
32K
Creates 32 kilobytes per cluster.
64K
Creates 64 kilobytes per cluster.
/q : Performs a quick format. Deletes the file table and the root directory of a previously formatted volume but does not perform a sector by sector scan for bad areas. You should use the /q command-line option to format only previously formatted volumes that you know are in good condition.
/f:size : Specifies the size of the floppy disk to format. When possible, use this command-line option instead of the /t and /n command-line options. Windows accepts the following value for size:
1440 or 1440k or 1440kb or 1.44 or 1.44m or 1.44mb
1.44-MB, double-sided, quadruple-density, 3.5-inch disk
/t:tracks : Specifies the number of tracks on the disk. When possible, use the /f command-line option instead of this command-line option. If you use the /t command-line option, you must also use the /n command-line option. These two command-line options provide an alternative method of specifying the size of the disk being formatted. You cannot use the /f command-line option with the /t command-line option.
/n:sectors : Specifies the number of sectors per track. When possible, use the /f command-line option instead of this command-line option. If you use the /n command-line option, you must also use the /t command-line option. These two command-line options provide an alternative method of specifying the size of the disk being formatted. You cannot use the /f command-line option with the /n command-line option.
/c : NTFS only. Files created on the new volume will be compressed by default.
/x : Causes the volume to dismount, if necessary, before it is formatted. Any open handles to the volume will no longer be valid.
/? : Displays help at the command prompt.