If my father passed away several months ago and I'm pretty sure I am a beneficiary, how can I find out if I am or not?

You are a beneficiary by statute if no will or trust exists, and any estate he would have would have to be probated. If a will does exist, then the will is also probated and the named beneficiares would inherit and would be notified. If assets were left in a trust then the trustee must notify the beneficiaries so designated therein of the trust and send a copy on request to the designated beneficary.