I have a Dyson vacuum

Question

I have a Dyson vacuum cleaner ...upright....all of a sudden my vacuum started making this awful sound...like a loud buzz...but only when I have it on carpet....when I have it on "floor" mode it's fine....sometimes(although seldom) it has worked without buzzing...and it's LOUD!!....I have only had this vacuum for a year....and no...I have never picked up any coins or hard stuff.only use it for 2 rooms.the rest of the house is wood floors.......what shall I do?Thanks......Gloria