How to go back to a page and show everything as it was in this page

I have a aspx page1 with a DropDown box. When I select a value in this DD box, a gridview1 is shown. Then I select a record in the GridView1 and click a Button1, another GridView2 is shown. Then I click Button2. This will redirect me to aspx page2. What I want is when I press go back button in page2, I want to see the page1 with all the selected values in DropDown Box, GridView1, GridView2. The problem I have now is that when I go back from page2 to page1, the page1 shown with empty DropDown box, empty GridView1, empty GridView2. So how to solve it?