How to Access MasterPage Control Property in Content Page

Create object for control in content page which you want to access and initialize it like this

TextBox l =(TextBox) this.Master.FindControl("TextBox1");

//here Textbox1 is id which is in master page

Label1.Text = l.Text;

//Label1 is in content page which get the text from master page

       

l.Text = "Done...";

//set some text to control which is in MastePage