Windows 10 keyboard not working when logging in?

I can't log in to my laptop for unknown reasons, or I can't enter the password because the keyboard does not respond and if then only very delayed. What should I do?

Swap the keyboard or at least the port to which it is connected. Say, plug in somewhere else.

I forgot to mention that I'm using a laptop

If it responds very slowly, the system may also be working at full capacity. Maybe an older computer. Wait two minutes so that he can charge all his services etc. And come to rest. Then he should have free resources to accept your registration.

You could also connect another keyboard, but then it is not a successful solution.
The problem is really due to the system load. Simply uninstall everything you don't need. Update drivers. Let Windows update too.