Airport won't connect to the internet anymore after unusual reset

About a month ago, I was using my Mac normally.

Then one time when I had it on, it just resetted by itself. I don't know how. I don't know why, but it resetted. It turned off by itsel. Anyway. I turned it back on, and then I found out I could no longer get Airport to connect to the internet.

I then got a message that said "Your internal clock has reset, this may cause some programs to behave eratically".

Ever since I haven't been able to connect to the internet, but I have reset all of my clocks back to normal.

Sometimes 3 Bars from my internet connection show up when I start up the Mac but then my internet says connection error.

Afterwards, the three bars go away and my Airport says "!" .... and it picks up no internet connection even when my routers are on. I'm using another computer at the moment and it can connect to the internet successfully.

So I believe it is a problem with Airport.

What should I do to get my internet connected again, even though it already works? My Mac works fine otherwise !