My Iphone 4s won't connect to wifi any fixes?

My Iphone 4s recently stopped connecting to wfi. I have no clue what could have caused it because I haven't done anything different with it from when i got it,except install apps i guess. I looked it up and people are having similar problems, but couldn't find the right solution to fix it. Reset my phone, even restored it and that did nothing. When i have the wifi screen open it's like the option to turn on wifi isn't working it's just grey and cannot be clicked. Also i noticed bigger apps with more memory do not work on my phone its just exits out of the app. I'm saying this because i spent some money on an app and that is no longer working. Also i'm using up my data a lot more frequently. If there is no fix is it possible Apple would compensate for the app i paid for?

Please message with any info you may have

Thanks