by Ken Task.
Got me! Have not a clue ... but guesses ... in the config.php file each variable there should be enclosed with 'ticks' or quotes and end with a ';'. That omission usually renders a blank page, however.
And, since you may have been editing the config.php file ... you didn't do that with Word, did ya? ;) Seriously though, at the bottom of a 1.9 config file this comment:
// MAKE SURE WHEN YOU EDIT THIS FILE THAT THERE ARE NO SPACES, BLANK LINES,
// RETURNS, OR ANYTHING ELSE AFTER THE TWO CHARACTERS ON THE NEXT LINE.
The only other thing I can think of is error on search and replace in the DB.
'spirit of sharing', Ken