Why won't my iPhone 4s connect to Wi-Fi?

I just got it a few weeks ago and my iphone 4s won't connect to Wi-Fi. It worked at first but it isn't working anymore. Its not an issue with the router or anything because my iPod and my Nook both connect just fine. I have a lifeproof case on it and some places said it could be the case. Do you think it is the case? I tried resetting the network settings. And i turned the phone on and off. Sometimes the button to turn the Wi-Fi on and off is gray or faded so it won't even let me turn it on. But sometimes it lets me turn it on but won't detect my Wi-Fi. I tried typing it in in the other box but it gave me a message that said something like can't scan for wireless networks. Could it be the case? Or is it the phone? Is there a certain combination of settings that have to be on?

You should have both Wi-Fi and ask to join networks on. Under general settings there should also be an entry for Wi-Fi address. If this item is missing, you will need to contact your provider. In addition, you should not be in airplane mode unless you also have Wi-Fi turned on. If none of these apply, then take the phone out of the case and see if you can now connect. If you do, then the case is the problem and you will need to get a new case.

Not helpful. I erased a back up and reset the network and now I can't add a network so I have to physically go to a sprint store to reset my network? All I wanted to do was back up my iCloud and it was deselected. I don't understand why I can get on safari and write this message but I can't do a backup. Now that I've followed all of the instructions, I have to go to a store. Very frustrating.