The BRAT diet. Its been around a long time. Bananas, Rice, Applesauce, Toast. The rice must be plain, and the toast also. These 4 items should be the only things you eat for as long as it takes for the diarrhea to stop. If this problem occurred after taking antibiotics it will be harder to cure, then i would recommend taking acidophilus three times a day.
One of the most commonly used home remedies for diarrhea is the banana remedy. Mash a ripe banana, mix with 1 tsp of tamarind pulp and add a pinch of salt. Take twice a day. Check out some more remedies from www.home-remedies-for-you.com/remedy/Diarrhoea.html.