If your toilet won't flush properly, you can typically resolve a clog using a plunger. Do not flush a toilet that is clogged, as this could cause the toilet to overflow.
If your sink or shower won't drain properly, there may be hair or other debris in the drain. You can attempt to clean the drain using a cleaning tool, but please do not use drain cleaning chemicals, as these could damage your plumbing system.
The central thermostat in your rental property controls the heat and air conditioning. Locate the thermostat and check that all settings look correct. You may be able to cycle the system off and back on again to restore the defaults.