my daughter is 3. the birth father is just now wanting to be in her life. does he have rights? will the court give them to him? can i do anything to prevent this?

He can go to court and get them awarded and there is very little you can do to prevent it. You are entitled to child support, however.

Unless he donated the sperm under a signed agreement where he gave up his rights, then of course he has rights.

Unless you can show he would be a danger to the child, there is little you can do about it. You may be able to impose supervised visitation and you should definitely ask for child support.

I think you need to clarify. You first referred to the child's father as a sperm donor, then referred to him as the birth father. Were you calling him a sperm donor because that was how you conceived? Or was it merely a swipe at him by implying that's all he was to you, as he hasn't been present in the child's life?