Having trouble connecting my iphone 4s to my home Wi-Fi?

So basically, my iphone won't connect to my home Wi-Fi, even though it was working fine last night. Whenever I try to connect to my home network it just shows that annoying loading circle thing. Here's what I've tried to fix it so far. With no luck:

-Reset the router
-Rebooted my phone
-Disconnected from the network, then reconnected and entered the correct password
-Reset network settings on my phone
-Manually entered the network information rather than selecting it from the list

I'm seriously clueless. I don't know what else to do. I've tried searching online, and none of their solutions helped me at all.

FYI, my router is Verizon Fios. And my sister, who also has an iphone 4s, was having the same problems earlier.

Set the router encryption for Mixed. The phone might require WPA, WEP, or something similar.mixed makes it available under multiple types of encryption.
if you don't have mixed, go through a manual connection process. It will let you know what kind of encryption you need to set your router to. You will also need to change all the computers on your network.

if none of this works, get a linksys ea6500 or ea4500.