Why can't I turn the Wi-Fi on my iPhone?

Today I dropped my iPhone 4S and it turned its self off after so long I turned the phone on again by holding down in the lock button and the button home button and now it's not giving me the option to turn my Wi-Fi on, what do I do!

You drop it on the ground again. But this time do it harder

You take to an apple store who will take it away and repair it,
HTH
David