How to return an usb pendrive to its original windows format

The problem is solved.
It's just that there was a partition the size of an CD and the rest of the space was not assigned.
The solution: Using System Admin tools delete the single partition and then create a new one with the size of the full pendrive.

I got 3 separate partitions with 950MB each (only on visible in windows explorer). In windows vista, the storage management feature isn't able to delete these partitions ("operation not supported on removeable media") or to create a new one on the spare space.

So at the moment I have a 16GB pen reduced to 950MB.

Any ideas?

TIA

I've got the same problem as fernando. The options to expand, shrink and delete the volumes are greyed out in Disk Manager are greyed out. My 4 GB flash drive is reduced to 950 MB. :(

I have the same problem as sjdvda and fernando, the options to expand, shrink, etc are greyed out. I have tried using the tools in Windows 7, Vista, and XP to no avail. I have also tried to use Acronis Disk Director Suite to solve the problem, but it has not helped. It says the unalocated space is ext3 or something, and cannot fix it. Anyone got any solution? (I want my 8 gig flash drive back)

I had this problem and finally found the answer by using the "HP USB Disk Storage Format Tool" [google it].

I found the method!
Windows7 is necessary for it.

1)Execute diskpart on cmd.exe (or Win-R)
2)DISKPART> list disk
3)DISKPART> select disk x
  x is the number of the USB drive.
  If you make a mistake, it is sure to become a large disaster!
4)DISKPART> clean
5)DISKPART> exit

The usb memory revived by this.

What does this tool does to usb drives? I mean, it shouldn't have this nuke effect on them, especially when there are far better alternatives, like Unetbootin.

I (somehow) lost my cellphone memory, which was connected at the time to my computer. And I don't know how to get back my memory, let alone the files in there.

And I didn't even got to try Chrome OS!

So, yeah, crappy app is crappy.

Two and a half years later. Thank you sugi you got on the right track and I successfully cleaned the card. Then I had a about 8 gig NTFS Unallocated. So now you need to reboot to apply changes then open Disk Management from Windows search.
You will see your "disk" full size in one Unallocated partition. Right click the partition and select Create simple......OK.....OK and it will default format your drive to FAT32. Home and dry. Damon

In Windows 7 - run diskmgmt.msc
The USB drive will show up there, with the reduced capacity. Right click within it and select 'Delete volume'
Now the whole capacity will show up, albeit as unallocated space
Now right click within that space and create a new simple volume. Set it to format as FAT32 or NTFS and bingo, you have your old USB drive back. (Needless to say all the data on the drive will be deleted)

Bootice worked very well. I'm back in shape with 8 GB.

Tobin Davis suggests this article as an answer to your question:
FAQ #1927: “My Xgb pen drive was reduced to Ygb”.

I used this and it worked like a charm.
http://erlern.wordpress.com/2010/04/02/repair-unallocated-space-from-usb-flash-drive/

sugi (buy-vtecpower) is right his method worked Thanks sugi (buy-vtecpower).