What should I do if I was claimed as a dependent by a parent, but they have been absent and not financially helpful in four years? I filed my own taxes, but got rejected.

This will take time, but the only way to resolve the situation as you stated is to file your taxes by mail.

• The IRS will see that both of you are claiming you as a dependent.
• They will send both of you a tax notice,
• You will each have to state what the situation is.
• The IRS will determine the outcome based on each of your statements.
• If you are verified you will get the refund you submitted and "he" will have to pay it back.