Solution is based on the following thought: The value of a common ancestor has to always be between the two values in question.

static Node lca(Node root,int v1,int v2)
{
    //Decide if you have to call rekursively
    //Samller than both
    if(root.data < v1 && root.data < v2){
        return lca(root.right,v1,v2);
    }
    //Bigger than both
    if(root.data > v1 && root.data > v2){
        return lca(root.left,v1,v2);
    }

    //Else solution already found
    return root;
}