Unable to update my iPad mini. Unable to install new programs.

Your iPad Mini is probably third generation or older (see Settings > About for details), and is thus too old to update past whatever iOS version it’s presently running, as that iPad Mini lacks the hardware and the memory for newer iPadOS software.

iPad Mini third-generation will not upgrade past iOS 12.

There are no hardware upgrades for iPad, and the only option is a newer or new iPad.