Hi... wifi is grayed out on my iphone 4S. Tried resetting the NW settings, also erased all the settings to a new iphone. Even then the problem is not solved. Please help.

Try the suggestions here to see if they resolve your problem:

http://support.apple.com/kb/ts1559

If these don't work you may have a hardware problem. Visit an Apple store for an evaluation or contact Apple Support.

Use this article: support.apple.com/kb/ts1559

Follow all of the troubleshooting steps. You can even try restoring the device as new: support.apple.com/kb/ht4137

If the wi-fi remains greyed out, your device needs service.

If within warranty, it should be free.

If not, it will probably cost $199 USD + tax.