How do i find out if my late father had a Will and if I was left anything?

You can check with the probate court to see if a Will was filed. If it was you (or any one else) can get a copy as it is now a matter of public record. If a Will has not yet been entered, you can find out if one even exists since in the eyes of the law you are what is called an "interested party". This is someone who would inherit if there is no Will (pursuant to something known as "intestate succession"). Therefore, since whether or not there is a Will affects your rights, you have a stake or "standing" which is a sufficient enough interest to give you the right to bring a legal action to view it if it exists. If your faher had no Will, then you stand to inherit as one of your thater's heirs since he died "intestate". Under FL law, you are entitled to 1/2 of your late father's estate. Just be aware, however, that some assets pass outside of probate such as IRA's, 401k's and the like; they go to directly to the named beneficiary.

There is no good or certain way, if you father did not provide you a copy of said will. You could sue his estate claiming that it is your understanding that there is a will, and in that process use legal processes or mechanisms to request information about or a copy of a will--but if your stepmother claims there is none and refuses to provide a copy of same, unless you have some independent evidence thereof, there is really no way to go any further: if she has the only copy and destroys or hides it, there is no way to prove otherwise. You could also ask his lawyer, his accountant, etc.--one of them may know.
But in your state, if there is no will, then since you are your father's child by someone other than your stepmother, you are entitled to inherit 1/2 of your father's property. So the real thing to do is to sue his estate for the share you are entitled to under "intestate succession" (if there is no will); in that lawsuit, you can get information about his assets, including verifiable information, like requesting all his bank account statements, any deeds, title to any cars, etc. Your stepmother could only defend on the basis of producing a valid will and showing the will leaves it all (or at least more than 1/2, which is what she gets under intestate succession) to her. Ideally, hire a probate attorney to help you; if you can't afford one, you can file the legal challenge yourself ("pro se"): contact the clerk's office for the probate court in the county in which your father lived.