First thing is to try and mount it read only, it looks like that can work in some cases. Select it in truecrypt as normal, but when you get to the password input section, click on the options button. This expands some additional things, check mount volume as read only. That will possibly let you access the content on the USB. If it does, I suggest storing it to an encrypted file container temporarily, and then formatting the USB device and re-encrypting it with truecrypt, making sure to select some filesystem that is compatible with whatever OS you are using, then you can put your content back on it and wipe the temporary encrypted file container. That is the first thing to try anyway. It looks like it can also be caused by corruption, in which case you may be fucked unfortunately. It also looks like it can be caused by trying to mount a filesystem that is not compatible with your operating system. That is just what I can gather from a quick google search, let me know how that works for you and if it doesn't I will try to find something else for you to try.