Dell wifi application is not working

Hello, techyv experts,
I need help for my dell wifi application. I have been using Dell N5110 Laptop with windows 7 for 1 year. I was using wifi in my laptop without any problems. But it is showing problems for more than 10 days. The problem is that it is connected with internet but doesn’t load anything more than home page. It just says that Server not found. I don’t know what the problem with my dell wifi application is.
I am using firefox as internet browser.
Can anybody help?
