The first question you have to answer is "What is down there?" If you know it's a child's toy or other hard object, it may be time to call a plumber. If you end up pushing it further down the pipe and making it harder to get to, it could end up being more expensive to fix the problem.
5 Easy ways To Fix A Clogged Toilet
A good seal under water is required for a plunger to work properly. It's the force of water, not air, that will cause the clog to clear. If the bowl has drained, fill it with water from the sink until the plunger is under water. You can also run the plunger under hot water to soften the rubber to ensure a good seal.
Be careful with that first push, because there will be air in the seal. This is especially important if there is water in the toilet that you definitely don't want splashed around. Once you get a good seal, push and pull up firmly without breaking the seal. It can take ten to twenty pushes to dislodge a stubborn clog, so don't give up. Check your progress by breaking the seal and seeing if the water drains out. If it does, flush the toilet to see if it drains properly. If it does, congratulations. If not, make the seal and plunge again. Sometimes this cycle needs to be repeated three or four times before a clog is fully dislodged by being broken up or pushed down the drain.
Chemical drain cleaners have very caustic chemicals that should not be inhaled. Follow instructions and use only the specified amount. Also make sure that the product is specifically made for toilets. Make sure that the room is properly ventilated, and do not use a plunger after you pour the chemical in. You risk splashing it on your skin.
Reaching the chemical drain cleaner step is an important decision point. If it doesn't work or you don't want to risk trying it because of dealing with harsh chemicals, it's time to call a plumber.
You may want to check out our Plumbing Page for more useful tips and information.