Q: iPhone 4s.. my WI-FI screen is grayed out and not working

"Freezer" suggestion is good for ice cream only. You should follow instructions from more reliable sources.

Take a look at this article: If Wi-Fi is grayed out or dim on your iPhone, iPad, or iPod touch - Apple Support

If none of the steps above helped,  you may try to restore your iPhone or take it to the Apple store for further diagnostics. In order to restore it plug your iPhone into iTunes and restore it as new(hopefully your did a backup)

Here you may find info about restore: Use iTunes to restore your iPhone, iPad, or iPod to factory settings - Apple Support

Good luck.

light heating on the wifi chip located next the LCD connector on board .100%