The answer to 'how to unclog P-trap' is to remove the P-trap under the sink and clear any debris or blockage. This is a common plumbing issue that homeowners can often address themselves with a few basic tools.
First, place a bucket under the P-trap to catch any water that may spill out. Then, use a wrench to loosen the slip nuts on either side of the P-trap and gently remove it. Inspect the trap for any clogs or buildup, and use a small wire or plumber's snake to clear the blockage. Once the trap is clear, simply replace it and tighten the slip nuts back up.