If you want to get a teenager to clean up a messy room then the worst thing to do is shut the door and ignore the problem. The room will just get messier and messier. In fact if you do that the problem could get so large that the kid will never attempt to clean up. As a parent it is your job to get them to clean it up and organize it.
The first thing you should do is try and reason with your child. Don't nag him or her but ask him calmly and quietly why cleaning the room up is such a problem. Ask them what the problem is when it comes to cleaning up the room.
After talking, help them assess the room and find out if they need shelves on which to store their music or other knick knacks. If your kid is a teen there might be a lot of make up around. Be clever about what you can store things in. Old cups and bowls can be used to store items. You can also use plastic tubs. Old boxes and shoe boxes can be good free storage containers for smaller items as well.
You can put smaller boxes inside drawers to help the teen stay organized as well. Get organizers with shelves and label the drawers and organizers so they know where to put things each time they clean.
One way to encourage them to get the room looking clean is to have them try to get all surfaces clean. This gets them out of the habit of cluttering up surfaces all of the time.
Kids that have messy rooms sometimes do not have the basics. They will need a place to store pencils, pens, calculators, rulers, art supplies and glue. Plastic tackle boxes and plastic work boxes can also help a disorganized teen keep things straight.
To help reduce the amount of trash that might be lying around make sure that you place trash baskets in strategic spots and designate a day when they must take out their own trash. Keep a tote basket full of the cleaning supplies he or she will need to keep their bedroom upstairs pristine. This prevents them from experiencing'the drat' of searching downstairs for the things that they need.
Once your child does master keeping the room clean then praise him or her so that they keep on doing it again and again. Reward them with movie tickets or something else they might prize to keep the motivation there in their heads.