If you're dealing with a drain clog, you may be able to solve matters on your own.
If you're troubleshooting a clogged toilet, use a plunger to attempt to push anything blocking the pipe through the system. Be careful as you do this not to flush your toilet multiple times, as this could cause your bathroom to flood.
Sink and bathtub drains can also be cleared with a plunger. If you choose to use a chemical like Draino, please do so sparingly, so as not to hurt the plumbing system.