The answer to this question depends entirely on the law of your state.  Florida has a statute of repose that bars all medical malpractice lawsuits if the malpractice occurred more than 4 years ago and a wrongful death statute that requires you sue within 2 years of death.  Many states have similar provisions.  If your father died 7 years ago, I doubt that any state would permit a lawsuit now, but you should call a malpractice attorney in your state immediately to find out.  They will probably tell you right over the phone if the claim has any chance.