If you are the only admin why do you not know the password?
when I type "passwd" as I have seen, no characters show up
If you mean no characters show when you type the password, yes that is correct and by design. You will not see any characters or asterisks or anything else. Just enter the password and hit the Enter key. It isn't really clear what your situation is though. Do you enter passwd and not see it on screen. If that's the case it could be a keyboard problem.