The biggest consequence of water damage is the growth of mold and fungi which is hazardous to your health. While this can cause strange odors,  and structural damage such as discoloration of walls, and sagging ceilings, this will drive down the value of your home.

First, immediately turn off the toilet’s water supply. It should be located on the wall behind the toilet. If the overflow continues it is a sewage backup. If the overflow stops, start with a standard plunger. Insert and plunge vigorously up and down. If the plunger fails, use a toilet snake, known as a toilet auger. Place within the tank by turning clockwise until the cable extends into the drain. Keep cranking until you cannot go any further. Gently pull back to feel the resistance. You have hooked the clog. Begin cranking counter clock-wise to pull the clog up and out. If this fails, contact your plumber immediately.