If you are using NTFS as your file system, and your USB drive was formatted with NTFS, some versions of Mac OS X can't write to an NTFS drive. This may be why he wasn't able to use the USB drive without reformatting it to Mac OS format. If he's already reformatted your USB drive to Mac OS then your PC will not be able to read the USB drive without extra software (like MacDrive), and so it will say it needs to format the USB drive back to a format that it can read. Even if you could read it, however, your original data will likely have already been affected by his reformat, and all you would be able to see is the data that he copied onto the drive after he reformatted it. It would seem to me that you will need some kind of data recovery software to try and get at your previous data on the USB drive. If you format it back to NTFS then that will only mean that there are two levels of formatting to try and undo, instead of just one, so your data recovery software needs to be something that can read the USB drive in its current Mac OS format. I haven't tried to do that before, but maybe someone else will know of some software than can do that.
I stupidly lent a Kingston USB stick to a friend (who's awful with computers) for one evening. It contains a ton of irreplaceable work for my university disseration. My life literally depends on being able to access those files, and now I can't - really hoping someone can help me...
My friend tried to use the USB to transport an imovie (he works on a Mac, I work on windows). For some reason he was unable to do this and tried to follow the instructions in this youtube video: http://www.youtube.com/watch?v=6TpS5dYkdZM
I don't know how well he followed the instructions but now whenever I plug in the USB it says it needs to be formatted for use, but warns that formatting the USB will delete all its contents, which I can't let happen!
Please, can anyone help?