It sounds like you have more detective work to do. Certainly you don't owe tax if this is not your father's IRA (such as, identity theft of his SSN, or a mistake by the custodian). You need to figure out what actually happened before you can determine what to do next.
Assuming is it not your father's IRA and this is a mistake or fraud, there are a couple of things you can do. Or, if it is from an IRA account that you didn't know about, you might need to report it. (For example, there might be a law in your state that says after so many years, abandoned accounts must be rolled over to a simple interest bearing account that does not have investment risk. In that case you report the rollover but its not taxable, and you contact the new custodian to withdraw the money.)
You don't know what happened so we don't know, you need to figure it out first. Don't just ignore it.
