are you over 19 as of 12/31/19 or ovr 25 as of the same date if a full-time student?;  do you provide over 1/2 your support?;  did you reside with your parents for less than 1/2 the year?

answer any yes and you are not a qualifying child

is your gross income for 2019 over $4200?; did you provide over 1/2 your support?

answer yes to either question you are not a qualifying relative

if you are neither a qualifying child nor a qualifying relative then your parent's were correct in not claiming you as a dependent  amd you should have answered the question no --   yo'll need to amend your return

if you are either, it's your parent's return that's wrong.  they can choose to amend if they wish.