What do I need to do to settle my deceased girlfriend"s estate if she had no will?

I cannot answer this question without more information.  If your girlfriend had no will and you are not listed on any property (house, bank account, car, stocks, retirement accounts, etc.), then you will have no right to inherit anything.  If a Florida resident dies without a will, the Florida statutes pass all their assets to relatives.  The only way to avoid this is to prepare a will or make sure the assets either include someone as an owner or as a beneficiary.

I am sorry for that bad news.  Perhaps it is offset by knowing that you are not responsible for any of your girlfriend's debts (unless you signed something saying you are responsible).  You have no obligation to open an estate or "settle your deceased girlfriend's estate."  You can let it all go into default and her creditors will have to open an estate to take care of the assets.

Good luck.  I am sorry for your loss.