no wifi greyed out.

I have an iPad 4 GSM and the wifi and bluetooth switch is greyed out. the iPad has never been dropped or been exposed to water. It is in pristine condition. I tried a method of placing the iPad in the freezer for 15 min and when i took it out, the wifi and bluetooth started working again. Unfortunately, it was only a temporary fix. What should i do to fix this myself. Is it possible to find the exact wifi chip and replace myself. Any help would be greatly appreciated. Thanks.