iPhone 4 with iOS 7 will not connect to WiFi any more!

This is really getting on my nerves because now when i use internet with me iPhone its just gonna go through 3G and charge me, when i have wifi! This is stupid!

Basically within this week my iPhone can no longer connect to ANY WiFi. Just to say i am typing in the right password, i have done a network reset, i have turned my iPhone on then off, i have done everything, but it just gives the messag "Unable to join the network ********" and at the top it says, "failed to join ********" I cannot be dealing with this and do not really want to do a system restore, plus the nearest apple store is miles away. I have also noticed today, my mother and her brand new iPhone 4s, was not connecting to WiFi for the same reason yesterday, please can someone help me out.