If you're moving it between Mac and Windows, you want to format your flash drive with the FAT32 filesystem. It shouldn't matter whether you format it on your Mac or on a Windows machine.
To do it on the Mac, plug in the flash drive, and open Disk Utility (in your /Applications/Utilities folder). The drive should appear in the list on the left of the DU window.
Select the drive, then click the Erase tab. On that tab, select MS-DOS (FAT) as the volume format, choose a disk name if you want to, then click Erase, and wait.
That said, if your drive just 'didn't work any more' after a while, it may be faulty and it's possible that re-formatting it won't help. (All flash drives do have a finite number of read/write cycles before they don't work reliably any more, too, although it's unlikely you've reached that limit through normal usage.)
Using Flash Drive On Mac
A new external hard drive or a USB flash drive that you just bought can be used with both Mac and PC, but not always straight out of the box because most of them (external hard drives or USB flash drive) are sold in NTFS format, which is fully compatible only with Windows. Larry: Erasing will erase the drive and set it up using the format you selected. I suppose if they used “format” then some people would think it meant to reformat the drive and somehow maintain the data. Once Disk Utility is open you'll see the list of available drives on the left. Choose the drive you'd like to format. NOTE that formatting your drive will erase the contents, so make sure you back.
Aug 23, 2008 1:22 PM