Many cases of no hot water can be resolved with simple DIY fixes like resetting a tripped circuit breaker or relighting a pilot light. However, call a professional for gas leaks, major water leaks, or persistent issues after trying basic troubleshooting.

Common reasons for no hot water in your house include a faulty thermostat, a broken heating element (for electric heaters), or gas supply issues like a pilot light failure (for gas heaters). Check your thermostat setting, reset tripped circuit breakers, and relight the pilot light if necessary. 

A standard tank water heater lasts about 8-12 years, while tankless water heaters can last 20+ years with proper maintenance. Factors such as water quality, usage, and regular upkeep play a significant role in their lifespan."