Can't turn on Wi-Fi on my iPhone?

This morning my home Wi-Fi wasn't working and when I was trying to connect it I accidentally turned my Wi-Fi off on my phone. I turned it back on again, or at least I thought I did? Anyway, I just checked because Wi-Fi wasn't working and it's not switched on, but it's not letting me slide the option over to switch it on. Any ideas? Help!

Added (1). I've restarted the phone twice and that hasn't worked.

Added (2). I have also restored it and that hasn't worked either.

Thats just to bad then aint it.

Reset the phone, hold the power and home button at the same time for 10 seconds let go of the buttons once you see the apple logo on the screen. Also try turning of your router off then back on. That should fix your problem.

Reboot your phone (press both buttons till it resets)

Restart your phone, or do a restore and it should work again