How do I get my keyboard to type letters?

Excuse me, I'm having a bit of trouble with my keyboard. I'm trying to type letters, but it's not working properly. Could you please help me understand how I can get it to type letters again? I've tried restarting my computer, but that didn't seem to fix the issue. Is there something I'm missing or a specific step I need to take to resolve this? I'd really appreciate any assistance you can provide.