Q: iPad Mini 2 won't connect WiFi

I've been able to surf the web on my iPad Mini 2 Retina always. When I woke up this morning it didn't connect to WiFi. It says the entered password is incorrect. I know it is correct, because I checked many times and my MacBooks work of the same network. I even connected my Android phone on this WiFi and it worked.

Here is what I've tried so far:

• Resetting Network settings
• Restarting the router
• Restarting my iPad

Nothing has helped.

I already checked out If your iPhone, iPad, or iPod touch won’t connect to a Wi-Fi network - Apple Support and other topics that I could find on this forum. I don't want to reset my iPad to factory settings. What I am supposed to do? Why does it all the suddenly say it's incorrect? I've used the same WiFi router for years on my iPad ever since I bought it.