Documented in Volume 1 of the UNIX Programmers Manual.
% reset
will reset the teletype bits to a sensible state by setting the terminal
to cooked mode, turning off cbreak and raw modes, turning on nl, and
restoring special characters that are undefined to their default values.
This is most useful after a program dies leaving a terminal in a funny
state; you may have to type
% reset
to get the shell to recognize it, as RETURN often doesn't work;
often none of this will echo.
It is a good idea to follow reset with tset(1).