Speech, touch
By talking
they can still hear you, so speaking works. as far as reading goes, if the blind person has learned brail then you can communicate that way too.
A blind axle is an axle which turns but does not communicate motion.
Time
Yes, very much in the same way that non-blind people can communicate with music. (Assuming they're not also deaf.)
Because they can't see you
to help blind children communicate or something
To blind side someone is to catch them off guard. To do or say something that someone was not expecting.
To send messages, a blind person can use a computer with a Braille keyboard. To read messages, one would usually touch a piece of paper, plastic, wood, etc. that has Braille on it. Otherwise, you can communicate with a blind person regularly.
A dumb man might struggle to communicate this complex situation to a blind man. They might use simple words and gestures to convey that someone (the duff man) had taken the blind man's bag. They could also try to find assistance from someone else to help explain the situation more effectively.
Deaf and Dumb/Speechless people communicate by normal sign language, as they can still see. If you mean deaf and blind, they communicate by having someone tap out the sign language on their hand and then replying with normal sign language. The learning process is arduous.
hellen keller is important because she was blind and deaf but she could communicate