You can solve this problem by using these solutions:-
1.By Setting the MaintainScrollPositionOnPostBack property of Page to true.
Page.MaintainScrollPositionOnPostBack = true;
2.By Using SetFocus method of Page.
Page.SetFocus(your_controlID);
3.By JavaScript function.
window.scrollTo = function (x, y) {
return true;
}
I hope it will help you.
Best of luck.