Now I am of age my adoptive parents refuse to give me information on my adoption what do I do?

In certain countries , there are new laws about obtaining information about this.
If you can afford the legal expenses,
I advise you to seek them.
You can tell this to your adoptive parents before you do anything.

At the top of the adoption page, there is a sticky about searching for adopted children or biological parents.

Start by reading that.

NEXT--realize that your adoptive parents are not obligated to tell you one single thing about your adoption. LEGALLY, they are your parents. Has it occurred to you that they might have a good reason for withholding information from you? Perhaps THEY do not have much information--with international adoptions, it can happen that they have no information other than the adoption agency used.

First you need to give us the reasons your adoptive parents refuse to help you in your search before we can help you determine what your next step is.