Do you mean the old "Diskette", which is about 3.25 inches wide and has a hard plastic shell? I have a diskette reader that uses a USB port, so I know they exist. You could try to find someone in your area who has one. Someone like Kinko's might; them or the lab at the local junior college.
You should have more than one file; FOW makes about 20 for each data base. What error message do you get?
I have a Windows 98 machine with FOW 6 on it. If you'd like to send me the data from the flash drive as an attachment I will see what I can do. My e-mail as of today (6 Mar 2010) is email@example.com. (I don't plan on changing it, but these messages stay around for many years.)
I'd be happy to try to read the "2.5 disk" for you, if it is really a "3.25 diskette", but if it is your only copy, you don't want to send it to a complete stranger through the mail. Write to me.