HELP - add new line in text file without format changed

[newbie1818]

i get the script from other forum. but im still have problem with the format after processing.

this is my script.
@ECHO OFF
SET origfile="C:\Documents and Settings\user\Desktop\test1\before.txt"
SET tempfile="C:\Documents and Settings\user\Desktop\test1\after.txt"
SET insertbefore=4
FOR /F %%C IN ('FIND /C /V "" ^<%origfile%') DO SET totallines=%%C

<%origfile% (FOR /L %%i IN (1,1,%totallines%) DO (
SETLOCAL EnableDelayedExpansion
SET /P L=
IF %%i==%insertbefore% ECHO(
ECHO(!L!
ENDLOCAL
)
) >%tempfile%
COPY /Y %tempfile% %origfile% >NUL
DEL %tempfile%
pause

this script i save as run1.bat. after running, the format is out of order

original file
header 1<--here got tab delimited format--><--here got tab delimited format-->
header 2<--here got tab delimited format--><--here got tab delimited format-->
header 3<--here got tab delimited format--><--here got tab delimited format-->
details 1
details 2

output:
header 1<--tab delimited is missing--><--tab delimited is missing-->
header 2<--tab delimited is missing--><--tab delimited is missing-->
header 3<--tab delimited is missing--><--tab delimited is missing-->

details 1
details 2

[Janos™]

Maybe something like below can help you sort out the problem:

@echo OFF

:: Get the number of lines in the file
set LINES=0
for /f "delims==" %%I in (data.txt) do (
    set /a LINES=LINES+1
)

:: Print the last 10 lines (suggestion to use more courtsey of dmityugov)
set /a LINES=LINES-10
more +%LINES% < data.txt

[newbie1818]

where to i put this code under mine script? please advise