Scrape any loose food particles and grease into a garbage container with a soft spatula and then wash the loaf pan with warm, soapy water and a non-abrasive scrub pad. This gentle action may be all that is needed to clean the pan.
Sprinkle baking soda into the loaf pan and fill it with warm water. Baking soda will sometimes lift baked-on messes when used as a soak. Leave the loaf pan soaking for a few hours, or better, overnight. Baking soda is especially useful when foods are burned on.
Set the loaf pan in an empty sink and fill it to the top with boiling water. Cover this with aluminum foil loosely, taking care not to burn yourself. This creates steam that will loosen matter from the loaf pan. Let the water inside the pan cool naturally. After the pan is completely cool, dump out the water, gently scrape away the hydrated food matter and wash the loaf pan in warm, soapy water.