Rename all files to a numeric sequence

rename.bat

:: initial count
SET i=0
setlocal EnableDelayedExpansion

:: filter for extension, jpg as example
for %%f in (*.jpg) do (
  :: rename the current file to the new name
  ren "%%~nf%%~xf" "!i!.jpg"
  
  :: increase the counter
  set /a i+=1
)
:: prevent closing
pause