Wifi not working AT ALL.. How do I fix it?

We have an iMac 2011, running Mavericks. Recently, we have been having trouble using the internet via wifi, after my brother (who was using the computer) got blocked from the router. After doing so, he changed the mac addresses to circumvent the block. Fast forward, after it gets unblocked and everything... It still doesn't connect to wifi networks. Even in "Install OSX Mavericks" from an external USB, it does the same thing..

- Choose network
- Type Password
- Does that stupid connecting animation
- Ends up with a ! through wifi saying no internet connection
- Either says "Self assigned IP 169.bu.ll.sht" or "No IP address"
- Nothing works, tried new location, DHCP, new mac address, new computer name, net netbios name, all of that ****.
- I even tried using MY computer (connected to internet) to share the connection to the iMac, and that doesn't work. Ethernet does however work on the iMac.


I really don't know how to fix this.. I've done everything I know and it doesn't work. I've resorted to just using it via ethernet because it is too much of a hassle to keep trying the same processesses (recommended by the internet) that don't work.


What should I do?

 

yeah


turns out my cell hotspot works, and the other computer as a hotspot works.


It worked earlier today too, but now I'm having the same problems i've had since my brother got grounded. (we share this computer sometimes, and I left my long ethernet port at college which means I'd have to move the computer to the existing port)

ill try the prefs.plist thing now but I don't think thatll work because I couldn't get on via the "Lion Recovery" bit, so I guess something is glitched in the router that its still blocked *because the other device that got blocked worked fine