A friend has a Kingston 16gb USB drive that worked fine for several months, but now isn't recognised. I've tried it in my Toshiba running Vista, and the computer certainly knows there's something there - there's a connection sound and the light in the device lights up - but neither Windows Explorer nor Computer Management report it. USB reports it as an Unknown Device. Is there anything else I can try before binning it?
You could try browsing Kingston's USB Flash Drive support website(Link) for drivers for your thumbdrive. Thumbdrives are typically universally Plug-N-Play (excluding old Operating Systems), but in some rare cases a thumbdrive can become slightly damaged to a point where it's still functional but the defaul driver no longer works. A driver from Kingston may just solve your problem. Then, if that fails, feel free to bin it, because that's pretty much the only hope. Let me know how it turns out.