Apart from Dents and Scratches in the tube, impacts on the mechanism can cause serious damsge.
Do all the keys operate correctly?
Can you actually see the damage?
Repair is specialized, consult your Repairer.
Please do not hold an assembled Flute vertically by the Headjoint!
If they part company the damage can be ......
Flutes being sat on usually severely bent in the middle of the body.
Cleaning cloths jammed inside Flute bodies.
By looking carefully at the direction of the spiral of cloth around the cleaning rod it is often possible to remove by continuing its journey up the tube and out the other end.Avoid twisting the rod opposite the direction of the spiral it usually jams even more inside the tone holes.
Joints locked together.
Usually caused by grit trapped inside the joint, or, sometimes trying a friends Headjoint that doesn't quite fit! Pass on to a Repairer, before the problem is made inadvertently much worse.