If your toilet won't flush properly, there is likely something stuck in the system. You can typically use a plunger to unclog the toilet and push the clog through the pipes. Be careful not to flush your toilet until the clog has been cleared, as you may otherwise cause the toilet to overflow.
Most shower or sink clogs are caused by hair and other debris getting stuck in the pipe. You may be able to clear out this debris using a drain cleaning tool, sold in many hardware stores. Please refrain from using harsh chemicals to clean the drain, as these could potentially damage your plumbing system.
If you don't have hot water, locate the water heater for your rental home. Verify that all settings on the tank are accurate, and check to make sure the heater is currently on. If you make any changes to the settings, wait 15 to 20 minutes before testing the water temperature again.
If your A/C or heat isn't working properly, use the central thermostat for your rental home to troubleshoot the issue. Verify that the system is turned on and all settings are accurate. You may be able to turn the HVAC system off and back on again to restore the system defaults.