It's got a bang/bruise
The volume of a trumpet comes from how much air the player is moving through it. Blow harder and it sounds louder, back off and it gets softer again. Keep in mind that despite the name, trumpet mutes are not used to make the instrument softer; they are used to change the sound.
You really should be more specific...How you fix it depends on how you broke it. For about 95% of repairs, you should take your trumpet to your local instrument repair shop. They have all the tools and parts to fix it correctly.Without saying what's broken on it, there's now way to tell you how to fix it...
They blow into the trumpet with there lips tight and with a lot of air.
to reduce your sound on a trumpet, use a mute or play with less air
The soud comes from the trumpet player's lips vibrating. in a saxophone the reed vibrates.
the three valves on a trumpet push the air through different tubes, lengthening or shortening the distance the air has to travel. this raises or lowers the note.
Find a qualified air gun gun smith.
by air blowing into them
the vibrations from your lips
You buzz your lips, which causes the trumpet to vibrate. You change notes by pressing valves or blowing the air faster.
The player speeds up or slows down the speed of the air being blown through the trumpet.