If your wireless router has wired ports, plug a cable into your computer and directly into your router. If you get internet, then you know the connection between your dsl and router is good, and it is in your wireless settings. In fact, I would start by plugging into your dsl directly, if that is good, then plug the dsl into the router, and the computer into the router. That way, you test each one at a time.
While I don't think it is entirely necessary, when I am going t repower stuff, I turn on the dsl/cable router first, then the wireless/wired router, then the computer. The computer has to get an IP from the router, and the router from the dsl. Doing it in reverse, for me, seems to make sure each has a good IP.