I don't know FTM well enough to know if it has a hidden utility, but what you should be able to do is export the DB as a GEDCOM file and change:
1 NAME lastname /first/
1 NAME /lastname/ first
Then import that GEDCOM as a new family tree and see if everything is corrected.
To change the GED file you can open it up in "Notepad".
NEVER open one of these in a word processor program!