If your water goes cold, it's likely your water heater flame has gone out. You don't need any tools or a handyman to re-ignite the pilot light. Just follow these steps.
Newer model gas water heaters have built-in ignitors that can be used when the flame goes out. You just press a button (similar to how a gas grill works) and a spark will ignite the pilot light.
Older water heaters require a long lighter and a bit of manoeuvring in tight corners to ignite the flame. Before attempting to light the pilot, turn the gas line knob off and the dial all the way down. This will allow all the excess gas to dissipate which avoids flare ups.
Check out the video above for the full step-by-step.
How to light a gas water heater pilot light [House-Improvements (YouTube)]