No longer able to reach the Internet on Kali Linux

I'm running Kali Linux on VirtualBox and trying to learn some of its basics. I know it's based on Debian but I come from Windows so I'm new to Linux and networking in general.

My problem is that while I already connected Kali to the Internet and used Iceweasel many times, now, after some manipulations I did on the terminal, I can't reach the Internet anymore, even if I connect to my wifi network.

I tried the following:

$ ping www.google.com
ping: unkown host google.com

$ ping 8.8.8.8 
connect: network is unreachable

$ cat /etc/network/interfaces
cat: /etc/network/interfaces: Permission denied

i think my virtualbox settings are ok because i already surfed the internet before this problem came on but here are the settings ... i use a bridged mode on wifi intel(R) 5100agn in advanced tab i have all allowed and i use a usb ralink wifi adapter linked to the virtual machine

here is an img of the output of ifconfig -a

keep updating and here is the result of " cat /etc/network/interfaces " and " route -n"

after changing the vbox settings from bridged to nat nothing changed ... still dont have ip adress