I cannot type in my password on my start up screen on my mac air

Hi portsjoe,

Welcome to the Apple Community.

You might want to try working through these Apple Support articles, until you access your Mac

If your Mac doesn’t respond to key presses

Says:

If no keys work on your Mac notebook computer’s built-in keyboard

• • Your Mac may be showing a low battery alert that you can’t see.
  • Connect your Mac to a power point or connect an external keyboard to your Mac to see the alert.

Complete article: https://support.apple.com/en-au/guide/mac-help/mchlp1240/mac

If your Mac doesn't turn on

https://support.apple.com/en-au/HT204267

If your Mac doesn't start up all the way

https://support.apple.com/en-au/HT204156

Hope this helps you :-)