I've been locked out of my laptop and can't input the password. What can I do?

My laptop locked on me while I was using the Vietnamese keyboard, and now I am unable to input my password (I used the English keyboard for it). The problem is that I cannot input letters when I try to type in the password. I’ve tried connecting it to a different keyboard, but have had no luck. What can I do in this situation? To clarify, I am using a Mac.