If your sink or shower drain clogs...
You can normally resolve clogs using a plunger and some elbow grease. You'll need to create suction over the drain and pump the plunger up and down to push anything stuck in the pipe through the system.
If this doesn't work, you can buy a plastic drain cleaning tool at most hardware stores. You snake this cleaner into the pipe to snag any clogs and pull them from the pipe.
Finally, drain cleaning fluid can be used to dissolve small clogs. Do not use any corrosive chemicals that have not been certified safe for plumbing systems, as these could damage your pipe. If you're still having problems, you'll need to make a repair request.
You can easily unclog a toilet with a plunger. Press the plunger over the drain and push it up and down rapidly. Do not flush the toilet during this process or you may flood your bathroom.