Smells don't just appear out of nowhere. Something in your room is the source of the smell (dirty laundry, rotten food, etc). Find the source and remove it. If you can't identify it (too used to it?), then ask your parents to look for it.
If the smell seems to be everywhere in the room, consider deep-cleaning the carpets. (Buy/Rent a cleaner, or have a cleaning service come in.)
If you can't remove the source, all you can do is mitigate.
Leave the door to your room open to avoid stagnant air. Even if something is only mildly stinky, if you leave it in a sealed off room, the smell will permeate the room.
Consider getting an Air Purifier, which will churn the air in your room and filter it a bit. Make sure you stay on top of cleaning/replacing the filter in the unit.
If the smell is a musty/humid smell, consider a Dehumidifier. You will need to empty the drain pan periodically, or attach a drain line to your plumbing. You can also use Damp Rid.
Also, consider that the source of the smell may be you. Your parents may be trying to politely tell you something. Do you bathe every day? Do you wash your hair regularly (at least once every 2-3 days)? Do you put on a fresh change of clothes every day? Do you wear antiperspirant/deodorant? If you answer "no" to any of the above, it may be time to re-visit your hygiene.
Best Answer
To some degree, your garbage chute is always going to smell a bit like garbage. There are however some things simple and complex you can do to reduce it.
First, you need to clean it and ensure that any stuck food/grime is dislodged. Give it a hose-down (pressure washer if you can) and then disinfect/deodourize it. If there is crap stuck in there, it doesn't matter what else you do, it will keep smelling.
Make sure that whatever you throw down it is in a sealed bag; do not throw loose scraps down.
If it doesn't already have one, a flap on the opening will help keep some of the smell down - usually you have to push you garbage through it and then it springs back closed.
If you can control it, empty the garbage bin at the bottom frequently so food does not sit down there rotting (and smelling for ages).
As a commenter mentioned, positive pressure in the room will keep the smell from leaking into the room. Condo's use this mainly for fire prevention but it also helps keep smells at bay (or in the originating condo at least). A fan alone will not create the pressure, you need to be bringing in outside air at a faster rate then it escapes so that there is always positive pressure.