Password protected and secure, now I can't access wirelessly

I finally figured out how to secure and password protect my mac computer to my dell truemobile 2300 wireless router. Now, when I try to unplug the ethernet cable, I can't access anything wirelessly. The light for wireless is off on my router, and it appears for a brief moment when I type in my password, then it turns off and my computer says that it timed-out or that my airport connection failed. Any advice? Thanks so much!
Tracy

Welcome to the Forum. Have you tried a 'power off' 'power on' cycle for the Dell truemobile. Sounds like you need to go back into the Admin page of the wireless router and reset the Network settings.

Did you look at this page? Dell - Support