I need to make a batch file that will automaticly renamed files to numbers.
 

You could write something like the following:

rename.bat

set /a j=0

setlocal ENABLEDELAYEDEXPANSION

for /f %%a IN ('dir /b *.*') do (

set /a j=j+1

rename %%a !j!%%~xa

)


Edit:  The %%~xa preserves the file extension. Note, if you don't MOVE the resulting file to somewhere else, such as don't use rename but instead

copy %%a <some directory>/!j!%%~xa

it'll try to catch the renamed files, too...  So I'd use the copy and a temp dir, instead, perhaps creating the temp dir at the beginning of the batch file...