I suspect my sister is cheating me out of my share of an inheritance. What are my options?

If your half sister was the administrator, and not an executor, then your father likely didn't have a Will. If not, if he was not married at his death, and if you and your half sister are the only two children (either living or deceased), then you'd generally be entitled to 1/2 of the probate estate after debts, expenses, and taxes are paid. That assumes that there WAS any probate estate (assets that are owned by a deceased person and a surviving person as "joint tenants" and assets that are paid directly to a beneficiary OTHER than the estate under a beneficiary designation do NOT become part of the probate estate), and that the debts, expenses, and taxes didn't take all of the probate estate assets.  However, if you were an heir (or if your father had a Will and you were a beneficiary), then you are entitled to information. You've tried to get information from your sister directly, and from your father's attorney (which makes no sense; your father does not have an attorney after he's deceased- your sister, as the administrator, would be the one who would normally have an attorney), and you haven't been able to get it. Your next steps are basically (1) contact the probate court of the county where your father lived at his death, and ask for a copy of the entire probate file, and (2) once you have the file, hire your own attorney to help you review it and figure out your next steps. If resources are a problem, which based on your post I assume they may be, then you may be able to get some free or low-cost attorney help through a volunteer attorney program (Fulton and DeKalb County Probate Courts each run a program with volunteer probate attorneys for probate-related issues- you can find out more from the courts, and other Georgia courts may have something similar). You may also be able to find an attorney who is willing to take the case if it looks like there may be assets to recover, although most probate attorneys don't do contingency work. You should look for an attorney with a lot of probate experience, preferably including litigation experience. Best wishes to you.