d.h.s took my son away from his grandparents while I was present but wouldn't tun him in my custody and I'm his biological mother. What can I do?

To start with why did your grandparents have custody of him rather than you?

There are a LOT of unknowns here... Kids are taken away from their biological parents all the time for a number of reasons.

You should hire a lawyer and find out the details first. They are going to act in what they see as the best interest of the child.

With what little information you have provided or been able to provide...its impossible to guess.

The burning question is WHY did they take the child from your parents? Did they have legal custody? DHS is the one to ask what can be done about it.

Based on the very little info you provided we can only advise to a) talk to DHS and ask them what you need to do or b) hire an attorney.

If, however, you explain the background, we may be able to advise further. Why did the grandparents have the child? Did they have legal custody? Why do you not have custody? Where is the father? Why was he taken away? Why wouldn't they give him to you? Where is your son now? And, any question on law needs to include your general locale as laws vary by area.