Now this is what I get:

root@0[knoppix]# ll /dev/scd[01]
-rw-r--r-- 1 root root 0 Sep 4 19:36 /dev/scd0
brw-rw-rw- 1 root cdrom 11, 1 May 30 2001 /dev/scd1
root@0[knoppix]# rm /dev/scd0 /dev/scd1
rm: remove regular empty file `/dev/scd0'? y
rm: remove block special file `/dev/scd1'? y
root@0[knoppix]# mknod -m 666 /dev/scd0 b 11 0
root@0[knoppix]# mknod -m 666 /dev/scd1 b 11 1
root@0[knoppix]# rm /dev/cdrom /dev/cdrom1 /dev/dvd
rm: cannot remove directory `/dev/cdrom': Is a directory
rm: cannot remove directory `/dev/cdrom1': Is a directory
rm: remove symbolic link `/dev/dvd'? y
root@0[knoppix]# ln -s /dev/scd0 /dev/cdrom
root@0[knoppix]# ln -s /dev/scd1 /dev/cdrom1
root@0[knoppix]# ln -s /dev/scd1 /dev/dvd
root@0[knoppix]# ll cdrom cdrom1 dvd
ls: cdrom: No such file or directory
ls: cdrom1: No such file or directory
ls: dvd: No such file or directory
root@0[knoppix]# rmdir /cdrom /cdrom1 /dvd
root@0[knoppix]# mkdir /cdrom /cdrom1 /dvd
root@0[knoppix]# chgrp cdrom /dev/scd0 /dev/scd1 /dev/cdrom /dev/cdrom1 /dev/dvd /cdrom /cdrom1 /dvd
root@0[knoppix]# ll cdrom cdrom1 dvd
ls: cdrom: No such file or directory
ls: cdrom1: No such file or directory
ls: dvd: No such file or directory

root@0[/]# ls -la /dev/cdrom*
/dev/cdrom:
total 40
drwxr-xr-x 2 root cdrom 4096 Sep 5 06:58 .
drwxr-xr-x 14 root root 36864 Sep 5 06:59 ..
lrwxrwxrwx 1 root root 9 Sep 5 06:58 scd0 -> /dev/scd0
lrwxrwxrwx 1 root root 3 Sep 4 19:54 sr0 -> sr0

/dev/cdrom1:
total 40
drwxr-xr-x 2 root cdrom 4096 Sep 5 06:58 .
drwxr-xr-x 14 root root 36864 Sep 5 06:59 ..
lrwxrwxrwx 1 root root 9 Sep 5 06:58 scd1 -> /dev/scd1
lrwxrwxrwx 1 root root 3 Sep 4 19:44 sr1 -> sr1

I don't know what was done but I'll try it.

DVD drive still works right but cannot even read a data disc with cdwriter (cdrom).