How can I help my dad recover from neglect?
Your situation sounds alarming, and I'm glad you're reaching out for help. It's not clear where your father is --- a nursing home? A hospicefacility? Regardless, the situation sounds unacceptable. I'm going to suggest two places to look for help. One is the nursing home ombudsman program (nursing homes are legally required to have ombudsman to deal with conflicts between management and families or clients). This webpage will help you find the office serving your dad. You should also take a look at this list of elder abuse resources published by the AARP.
If you're not getting immediate help from the supervisors of your father's facility; you need to go the next step to the government agencies who monitor nursing homes. Best of luck to you with this important task.