Answer

Ok. More than likely, you have damaged one of the ABS sensors. These sensors are mounted near the brakes and rotors. If you were driving through mud, either one of the sensors was clogged up or the "ring" that the ABS sensors reads got clogged up. Unfortunately, you will need access to a scan-tool that can read ABS codes to firgure out what exactly is going on under there. Most local AutoZone parts stores will read these codes for you for Free in hopes of selling you the part/sensor you will need to make the repair. You will also need to have access to this scan-tool to clear the codes as well. If you have cleared the mud from the area around the sensor, and it has not cleared the light by itself, there is going to b e a problem under there that is going to need to be addressed.