Join Date: May 2004
Location: near Bremen, Germany
I am assuming for the remainder of the post that you have no vital data on the pen drive, so if you do, please back it up.
Try opening Disk Utility (in Applications -> Utilities) to see if it shows up there when connected. In the list on the left, you should see both the device itself and, within, at least one partition.
If there is a partition: select the partition, then look at the bottom and tell us what it says for "Format".
If there is no partition at all, but the device itself shows up: select the device. You should see an Erase tab towards the top right, and should be able to create an "MS-DOS File System (FAT32)" partition.
If the device doesn't show up, that's indicative of a wholly different problem. For example, the USB port could not be working properly; try a different one, or try connecting a different USB device to the same port. Or, the drive could be broken.