I just received a used cast iron grill does any one know how to make it flatt again thank you:(

take to a blacksmith to pound it out for you - and since it warped already have the blacksmith check for any hairline cracks - better safe than sorry - never place a hot cast iron skillet in cool or cold water - it will warp or crack or break

a blacksmith can heat it to the right temps and fix it for you

Thank you very much Mama Mangia.

You're very welcomed - it's the only way to save it.