..txt files don't have records, only lines. You could copy the file and
delete sections. If you are referring to IMPORTING the txt file into
Excel there are macros to do that.
Breaking in half=copy file to an A file and a B file then open and
delete second half of A save, open B and delete first half. Notepad will
show a line location of your cursor on the status bar at the bottom of
the window.