My Wi-Fi is recognized by my iphone 4, and loads but won't connect. How can i fix this?

I have an iphone 4, and before my home Wi-Fi would connect instantly, but now when i go to my settings, the Wi-Fi keeps loading and loading, but the check won't appear. The Wi-Fi sign turns blue, but no check! It works on my PC, and my siblings andriods, but not my phone. I've tried everything, reseting the network, turning my phone off. Nothing seems to work. I'm using my 3G now.

Try "Reset All Settings" which will erase everything but i don't know, give it a try?