Wifi Greyed-out

Look in the "More like this" box to the right.

There are a lot of suggestions that MAY help...the starting point is work through http://support.apple.com/kb/TS1559 and if that doesn't help, a user found that what worked for him is:

Settings > Airplane Mode ON, and Do Not Disturb ON

Power down and wait 5-10 minutes

Power up

Settings > Airplane Mode OFF and Do Not Disturb OFF

and if thst still doesn't help, visit the Apple store genius bar for testing.

If these steps don't work, if you have done a reboot by holding the power and home buttons until the apple logo appears and it restarts, ignoring the red slider if that appears, the last option is a visit to an Apple store genius bar for testing by the technicians.

if your phone is out of warranty, to get it replaced, it does cost $199. this is a hardware issue, so that's why it needs to be replaced. if you want another option, you can take it to a third party iphone repair place. since you're already out of your hardware warranty, you won't risk losing your warranty. perhaps they can do something for cheaper, but you'll never know until you ask

tech support can't fix your hardware problem - only a repair or a replacement can

tech support is for software problems

that's not really a question. i don't know how else to explain this to you. What you're experiencing is a hardware issue. Something inside of your phone isn't allowing it to connect to any wifi networks. You can verify what I'm saying by hooking up your phone to your computer, then restoring it as new. At that point, your phone has brand new software on it that won't have any issues. It is then and only then that you can see 100% that any issues present can only be due to hardware - issues that require the phone to be repaired or replaced

Take it to an Apple store genius bar and have it tested.