16GB USB flash drive shows as 16MB and is unusable [duplicate]

If all else fails, boot an Ubuntu CD, plug in the USB drive, and format it there. Ubuntu seems quite good at formatting things that Windows considers otherwise untouchable. Once formatted, eject and reboot into Windows and attempt to use it.

This sounds like a partition issue, but if you bought it from the likes of Japanese sellers on eBay, be aware that some people are selling tiny (possibly old/refurbished/rebranded) USB drives, which report their size as much more. I poked around one a few months ago, and it even acted like it was still working past its real size, but just got a lot slower, and didn't actually store the data. I've only seen this done with cheap looking drives and unbranded or unusual brand names; not faking a reputable brand/product like Sandisk's. I suspect they've done that too though, or will try it soon enough.