This is the type of post where I blame myself for my stupidity (I'd call it rather carelessness)What happened? Well all I wanted to do was:
$ dd if=/dev/urandom of=/dev/sda3
Beware of the "3" at the end. I don't know what really happened but at the end dd was running with:
$ dd if=/dev/urandom of=/dev/sda
Damn! I was like: "F***! All my data!" Fortunately only 4 MBs were "randomized". That means: No partition table more! I tried gpart & co. No success! Backup all data and start from the beginning. So what's todays lesson? There will be hopefully no more "think before you type" post!!