Here’s how I restored the option to use Wi-Fi without resetting your phone. Try this method at your own risk. I have a second iPhone to test with so please be careful.
1 Power off device,
2 Wrap the device in a thin towel,
3 Place the device in a freezer for 30 minutes.
4 Remove from freezer and clean off any ice buildup,
5 Attach the charger before powering up device,
6 Now power up and check to see if your wireless option is available, *FYI* after the device has powered up you will notice the battery almost completely drain, that’s ok.
7 let the device charge up to 100% and do not power off device at this point. I’ve notice restarting the device resets and gray out the Wi-Fi option.
I tried this method a few times and it worked for me. If you fear moisture could be the problem then I suggest trying the rice in a zip lock bag method. Place the device in the rice then zip the bag. Leave the device in the bag in a dry location for 2 days. This should remove the moisture from most phones but does not guarantee your phone will be fixed. There are reports of the sim card removal working for some. Others use direct heat lamp or hair dryers, please be careful using these methods which could create irreversible damage to your phone.