Can't explain why Fn + F1 doesn't work, but reinstalling the wireless driver might turn WiFi back on, has to be worth a try.
Failing that, might be faulty F1 key. Try this:
1) Open NotePad or WordPad
2) Press F1 on it's own
It should open a new window for Windows Help & Support
If it doesn't, the F1 key is faulty.