My Wii will connect to the internet, but my Xbox 360 won't. Help?

I tried to edit the setting for wireless but it’s shaded grey & won’t let me select it. Iv’e checked online at the xbox website and nothing is working. I have got it to work before, a couple months ago. I decided to start playing again, but, I can’t get on xbox live without it connected.

Help me. Please & thank you.