To troubleshoot any toilet in need of repair, first identify the problem with the toilet, checking for the most serious problems first. Check for water along the base of the toilet. This determines whether there is a leak in the tank or the outflow pipe. Leaks from the tank may implicate a crack in the porcelain. A leak in the outflow pipe implies a leak in the wax seal.
If the toilet flushes slowly or the water does not shut off, open the toilet tank lid. Shut the water to the toilet off and clear the water from the tank. Make sure that the chain that connects the handle to the tank ball is properly attached and not tangled. Check the float arm for any defects.
If the toilet has a clog, shut the water off immediately to avoid an overflow. Use a plunger in the toilet bowl vigorously to fix the clog. A good indication that you have successfully cleared the clog is when the water rushes out of the bowl.
While many toilet issues require minimal labor, hire a professional plumber immediately if there is raw sewage entering the house or if leaking water is damaging the structure of the house.