There are many chemicals and tools that you can use to unclog the drain. It all depends on the size of the problem.
Plunger
This is the first tool everyone uses when it comes to leaking clogs. It is a very useful and very cheap tool and every home should have one. To use it right, place the plunger in the drain hole and push until a vacuum is created. The force and thrust a couple of times, until you feel that you have unclogged the drain. Test the water flow then.
Snake Plumber
It is also called an endless cable. It is a steel cable that has a handle that helps push the snake into the drain and then remove it. To unclog a drain, place it in the drain and then press and turn it gently to avoid damage to the pipes.
Hydro-cleaning machine
This tool is used by professional plumbers. Use a low pressure water jet to remove objects from the drain. It is best to have some waterproof cloths when you are using this.
Electric Snake Plumber
Electric snakes are almost the same as the normal drainage snake. The only difference is that they use a motor to remove any obstructions in the drainage. These are very powerful machines.
Copy of soda and vinegar
Copy of soda and vinegar is a home remedy for any clogged drainage. Just put a small cup of baking soda in the drain and then pour a cup of vinegar over it. The mixture is violently effervescent and interacts with the obstruction.
Hot water
Hot water is another home remedy for clogged drains, and usually does the job. It is best for grease drains. Just pour a bit of almost boiling water into the pipe and wait for a few minutes. Try to see if the blockage is still there.