Activation Lock was activated in my iPad Mini suddenly.

Hello,

The iPad is locked with Activation Lock. There is no way around unlocking Activation Lock without inserting the device’s associated Apple ID. If this is not an option you will have to find the original receipt for the device that clearly shows the serial number. Once you have this document you will need to take this document and iPad into an Apple retail location.

Activation Lock

See this link and hope you can recover your Apple ID --> If you forgot your Apple ID - Apple Support

And this for your Apple ID Password --> If you forgot your Apple ID password - Apple Support

If you are unsuccessful, without the original receipt, Apple won't help you.

Are you the original owner of the iPad, or did you buy it used?