HELP PLEASE....can't connect wirelessly

Let me start by saying that I know very little about how computers/networks, etc work.

I've had my macbook for a couple years (I don't even know how to find out what year it was made, I'd guess 2008). It just suddenly stopped allowing me to connect to the internet wirelessly at my house. I brought it to my college campus, where I've been able to connect all semester, and I cannot connect there either. I'm receiving wireless signals in both places with my phone.

When I go to system pref - network....and highlight airport, it says it's not connected even though i have all my bars at the top right of the screen.

It says "Airport does not have an IP address and cannot connect to the Internet."

I should point out that my brother's macbook pro still works fine wirelessly in our house.

Please help. Thank you.

I had similar problems in the past, as well as my Macbook Pro rev I and the last one that I bought about 2 months ago. I thought that would solve the problem, because it happened to me many times. The question is, keychains are a disaster, I had to delete my keychain and build more than I can count. I sat on the apple care for groped solve the problem once and for all, and I can say something different to me through the walk to delete my keychain so you can connect more than one connection.