Door was left ajar and now my freezer isn't totally freezing foods.

You need to open the back up and make sure the coil isn't a block of ice. This will stop airflow. You said you left the door open, this is a major source of moisture infiltration. The excess moisture can freeze the entire coil. Once the coil is completely defrosted, there should be a little switch somewhere that the door presses when closed. Plug the unit back in and press it. Make sure the evaporator fan motor is still working. If the ice blocked it there's a chance that it isn't working and needs replaced. The fact you saw frost buildup without taking anything apart tells me there's more ice needs thawed. Let us know what you find, please.