my wifi is greyed out on my iphone 4s is there a fix does anyone know?

[Ahmad]

Try this:

Settings > General > Reset > Reset Network Settings

And then re-connect to the network you want. 

NOTE: Doing this will make your phone forget every WiFi network it's remembered in the past and saved

[shimmerzz]

Did that didnt work:(

[Ginnungagap]

Heya Shimmerzz! Make sure to check out the following URL regarding this matter: http://support.apple.com/kb/ts1559

[bengjai]

Two things to try and fix. First, try doing a power cycle. Hold the power button down and the home button at the same time. Hold it for about 10 seconds until the phone turns off. Do not slide to turn off. Just wait. Reboot and try again.

If that doesn't work, it doesn't hurt to do a factory reset. Of course, back up your data either through iCloud or through iTunes. This way, you can find out for sure if it's the phones issue or just a glitch. Let me know if this works.

[rgl168]

If even following the recovery methods described with the Apple KB article does not work, you most likely have hardware failure.  Take it to Apple Store and have the phone serviced.