Once your pipes are flowing again, take steps to prevent a recurrence:
Always keep the faucet or fixture open so that as the ice melts, water has a place to escape. how to unclog a frozen drain pipe
If the freeze is in an exterior P-trap (common in older homes), you may need to approach it from the outside vent or cleanout. Once your pipes are flowing again, take steps
Here’s a step-by-step guide to safely unclog a frozen drain pipe. Once your pipes are flowing again
Look for frost on pipes, unusually cold spots on walls, or use a infrared thermometer to find the blockage. Methods for Accessible Indoor Pipes