Search:

You also need to change keyboard layout at boot, so append

knoppix lang=cs keyboard=cs

All boot parameters listed here:
ftp://ftp.uni-kl.de/pub/linux/knoppix/knoppix-cheatcodes.txt

Boot from the live CD and open a terminal and start photorec
Photorec is recovery software so there is a chance that you may get some data back. If some files have been partially overwritten then...

You may be unlucky with your VIA chipset as it has an unkown codec. TRy:
sudo apt-get update
sudo apt-get install win32codecs