Trouble with Home Network

I have been having trouble with my laptop ever since we came home for a few days off. I took it with us but I do have access to the internet. But every since we came on home I cannot get on the internet with the laptop which is wireless. It says that it is connected and with good signal but it will not go to the internet. The other two computers are connected by cat 5 cable and are working fine. And my brother-in-law has a Mac computer down stairs that is having no problems either. He connected using the Airport software.
I?m going into a week with no internet on the laptop computer.
I have tried everything.
If any one has a suggestion would be welcome
Thanks,
Tom