Pen Drive Contents Not Accessible

Hello,

I was using a 4 GB Kingston pen drive for a long time & this morning when I was working on it, suddenly power went off & later once same was restored & started to work, I found that I can't access any of its folders. When I take the cursor to it's folders, the message "Folder Empty" comes, But when I open the folders I see folders & content which cannot be read (in some codes such l?ï c ?.%çq ) . Also, I checked it's properties & Used Space Shows as 2.6 GB which is correct , but surprisingly when checking the inside folders, it's Size shows as 30GB, 19 GB & etc & etc, where as the pen is only 4 GB.
I even tried un-checking "Hide Protected Operating Systems" of Folder Options on Tools Menu, as same was recommended as a solution for a similar previous post. But I failed to restore my flash.
Highly appreciate if anyone could help me to bring it back. Thanks a lot.