Start by keeping track of how many phone calls/voice messages you have made/left. Next you could send a certified letter. If you still cannot get a response from your lawyer, consider calling the local bar association or Ohio Supreme Court's disciplinary committee. If your estate is damaged due to the lawyer "vanishing," you may also want to investigate a claim for legal malpractice, but be advised that Ohio's statute of limitations for filing a claim for legal malpractice is only one-year.
You should write him a letter and send it registered.
Be polite and detailed about your concerns.
Give him a short but reasonable period to explain.
If no response or a fluffy answer, file a bar complaint.