title: How to get value of TextBox before postback in ASP.NET
body: <p>I have a TextBox(enabled with PostBack). I need to store the value of it before it's postback. Is it possible? If so, can you please tell me how? </p>
  
  <p>Eg : I enter "10" in my TextBox. Then, in it's PostBack, a message box appears, telling "You have entered Ten!". Next, I enter "100" in my TextBox, this time, a message box appears and tells, "You have not entered the correct number!". Upto this point, it's Okay. But now what I need is, when I press the Okay button in the second mentioned message box, the number "10" should be displayed in the TextBox. </p>
  
  <p>Thanks in advance!</p>