Avast Firewall Won't Turn On

I run an Avast scan about every other week to make sure everything on my computer is running smoothly. I haven’t run one for about a month because of finals, and when I went to run a scan today Avast was somehow disabled. I restarted my computer, managed to get an update message for avast, updated it, and now it says the firewall is not on. When ever I try to turn the firewall on, it just says “unable to start firewall”. Any advice for how to get the firewall working would be greatly appreciated, as using my laptop any longer without it makes me a little bit uneasy.
Thanks.

Try a repair and reboot.

What do you mean? How to ‘repair’? Where to click the ‘repair’ button???

Repair Avast:

  1. Control Panel → Add/Remove programs → Avast
  2. Click on ‘Repair’.
  3. Follow instructions.
  4. Reboot.