The Data Recovery

I keep work on a pen drive and use hibernate. When I rebooted I forgot to put pen drive in. Now the pen drive is not recognised (says 0 bytes in computer management). I have searched on different forums. I know it is possible to reformat it, but I want the data on the pen. Please do not give solutions that say i.click on drive letter, ii. format it, or suggest data recovery programs that do not work when the computer is not recognising it as a drive.

Many thanks
Its not full, it is not recognising the pen as having ANY space. I think its a problem with the registry.

I have tried it with other computers (including linux) and no difference. These computers recognise other pens without a problem.
..and the problem with all the data recovery programs I have tried is that they cannot see the pen (in the normal filesystem the pen is not visible.. its only when I go into ‘computer/manage’ that I can see the pen is recognised by the computer, but listed as having zero bytes.