Unable to format USB stick to full capacity

PROBLEM : 

I have a 8GB USB Kingston stick that I haven't been able to format to the full capacity. It only shows 2.5GB when I look at the properties. I've formatted it both as FAT32 and NTFS and nothing has worked. When I do format, the drop down menu only shows 2GB.

However, when I open up disk management, I do see the other 4.5GB as unallocated space (so I'm not crazy). It won't let me add a new partition or even delete the existing available partition so I can format the entire 7.5GB as one drive.

Solution : 

We can use DISKPART from Windows OS to do so. Warning: DISKPART is dangerous - do not use if you don't feel comfortable with it! Insert your USB disk, make sure it is recognized by Windows (with the lower capacity), and then do the following:

1. Type "DISKPART" from the Command Prompt (accessible by clicking on Start and then typing "cmd" into the open field); you will then see the following prompt: DISKPART>
2. Type "LIST DISK" to see what number your USB drive is listed as.
3. Type "SELECT DISK 2" (if your USB is disk 2; replace # with your disk #); Diskpart will confirm that "Disk 2 is now the select disk.
4. Type "SELECT PARTITION 1" (this command selects what should be the only partition on your USB drive, the small one that you want to delete to get back the larger, full partition size). Diskpart will confirm with "Partition 1 is now the selected partition."
5. Type "DELETE PARTITION". This will delete the old partition. There are no warning prompts if you have existing data - make sure you have copied everything off before doing this! (If you get error "DISKPART CANNOT DELETE VOLUMES ON REMOVABLE MEDIA", run CLEAN command)
6. Type "CREATE PARTITION PRIMARY" to create a new, full-size partition. Diskpart will confirm with message of "Diskpart succeeded in creating the specified partition." You can type in "LIST PARTITION" to confirm the new, full-size. Wouldn't CREATE for me, so i used the CLEAN option, then Retried #6
7. Type "EXIT" to leave Diskpart. You can now format your USB drive by using the standard Windows formatting process.