My first encounter with Linux was on RPi.
I was trying differenmt commands, and was very happy with the power and control these commands gave me. while trying various commands without knowing exactly what they do I landed into trying the command sudo rm -rf /* , and that did it. However I quickly learned that the remedy is very simple: I just re-image the microSD card 
But I lost all my important data which I have saved on my ADS-B RPi, such as my Bank Account & Credit Card number and PIN, Offshore Account details, and most important, the list of phone numbers of all my Girl Friends. 