What’s your system? Apple? Someone had a similar problem. Btw, Apple sucks.
What’s your type of keyboard? MIDI? What happens if you unplug it and plug it again?
Do your keyboard has got a stuck key maybe? Do you have the same issues outside of Renoise?
Can you post a GIF showing your issue?
Some things you need to know:
Esc = activate/deactivate edit mode
Space bar = starts/stops the song (press it in case you want the song/pattern to stop immediately)
right Alt = starts the current pattern
the symbol that @BriocheBaps mentioned = pattern scrolling
left Ctrl + chosen number = edit step (DOES NOT work with the numpad)