Keyboard won’t work. Is split on screen

See >>> Split and move the keyboard on your iPad – Apple Support

To easily return the Split Keyboard to the full on-screen keyboard, you can either use two fingers (one on each of the two half-keyboards) and swipe the two halves together - or touch-and-hold the “keyboard” key, then slide your finger to the Merge & Dock option and release.

I hope this information and guidance proves to be helpful in resolving your difficulties.

Can you provide a screenshot? What have you done to try and correct it?