How do I recover deleted documents after improper USB ejection on Mac?

I've moved my pages documents to a usb stick. After I tranfserred them to my other computer some of those documents were deleted and when I go to open them it says "The operation cannot be completed because an unexpected error occurred." I think it may be because of the way I didn't disconnect the usb using eject... Can somebody help?

[Re-Titled by Moderator]