My parents adopted my child 3 years ago. I have always had total access to her. Now my mother and I have not spoken in about a month, and she is blocking me from seeing my daughter. I am the birth mother; do I have any rights as far as visitation goes?

It might depend on the terms of the adoption. If it was a so called "open" adoption, then you might have retained some rights.

But generally, when a child is adopted, the bio parents relinquish all rights to the child.

Even IF you have an open adoption, unless you are in MN or CA (the only 2 states that allow legal agreements between birthparents and adoptive parents), you still do not have any rights.

You would need to see a lawyer about possibly overturning the adoption because you were coerced if you wanted "rights". And really---that's next to impossible to do.

I'm in the same boat w/you. =( my parents have my daughter... I haven't seen her in months

No. If she legally adopted your child then you and the biological father had to have signed over your parental rights. This means you have no legal rights to the child.
If an agreement was not set up between you and your mother (i.e. defining visitation, your rights or involvement with the child, etc.) then you really have nothing to stand on, legally.
I'm sorry...