worksheet is not open and copy
 

hi,
in my pendrive i have lots of worksheet.suddenly some file cant open.cant copy, cant do anything.and the file name is change also..its show-"[G=@2i,@&?/l)....." this type of name.
when i try 2 open it give me a msg that- file name, volume,syntax is incorrect.
how can i solve this problem!!!is there is any solution!!