Computer will not detect SanDisk Micro 4G Cruzer

I have several SanDisk 4G cruzers, one of which my computer will not detect. It detects all the others. I’ve tried deleting the registry keys containing VID_0781 (some of which my computer would not allow me to delete) and that did not work. Anyone got any ideas? Maybe it’s damaged?? It worked yesterday.

Could be. Hopefully not. Try installing the software manually on you PC. Or at least try it on another computer.

How old is this stick by the way? 

It did after a reboot.  Before neither this 4GB nor an older 8GB could be recgonized.