Usb pen drive not working

[Daniel Vogel]

trying to backup some files from a server i plug my pendrive and mount it 
as:
mount /de/sda1 -t vfat /mnt/usb

but first i got problems, the folders that were inside got like ?--?-- 
<foldername>
so i coudn't open them.

After that i check it on windows, and they weren't shown but the "space" was 
filled with information (with no files or folders) so i guess it's still 
there.

The question is:
Can i restore the information? can i save it? or i just lost it?

I don't know wich kind of format it has...fat 16 or something else.

Thanks.