As you didn't want to list any of the '...several options...' you tried, this may be repetitive but the first thing to try is to just reboot your phone. A surprising number of people won't bother doing so when they encounter a problem, creating a situation where they're trying to fix a one-off issue. At least if you've restarted your phone and the same problem is still occurring that's a first step in actually trying to diagnose what's going on.
If after a reboot your WiFi menus are still greyed out, try enabling Airplane mode, and then try to enable WiFi again. Sometimes it just gets 'stuck' and needs to be manually disabled/enabled.
Also, have you noticed anything odd as far as Bluetooth connectivity? Inside some phones both WiFi and Bluetooth rely on the same antenna. This would indicate there's a possible hardware issue if you're also having Bluetooth problems. Could just be a matter of re-seating the antenna connector, but it does require opening up and possible disassembly. But something like this is more supposition than anything.
Has this WiFi issue been a long standing problem or did it just start happening recently? If recently has anything like a system update been applied around the same time?
