Clogged toilets are a common issue that you can generally resolve using a plunger.
If your sink or shower drain has clogged, you may also be able to use a plunger to move anything stuck in these pipes. Most hardware stores also sell drain cleaning chemicals and tools to remove small blockages.
The hot water heater in your rental property ensures a steady supply for your home. If you lose access to hot water or don't have enough available, check the settings on your tank and verify that everything is accurate.