>> sport=# select stat();
>> ERROR: fmgr_info: function 16556: cache lookup failed
Does *any* plpgsql function work? I think you probably broke plpgsql by
deleting its handler function, or something like that. Try dropping and
recreating the plpgsql language (then you'll need to recreate your
function, too).
7.3 contains interlocks to prevent this sort of mistake, btw.
regards, tom lane