The answer to 'P-trap no hot water' is that the most common cause is a problem with the hot water supply line or the water heater itself, not the p-trap. The p-trap is the u-shaped pipe under the sink that holds water to prevent sewer gases from coming up, and it does not affect the hot water supply.
Some common symptoms of a hot water issue include only getting cold water at the sink, the water heater not heating up, or the water taking a long time to get hot. Solutions may involve checking the water heater thermostat, inspecting the hot water supply line for clogs or leaks, or even replacing a faulty water heater. In most cases, diagnosing and fixing hot water problems requires the expertise of a professional plumber, so it's best to call one rather than trying to DIY.