Re: How to go back to previous page and keep all entered infomation

We have a lot of State Management techniques.
Use any of Client Side/Server Side State Management techniques to achieve your goal.

Here is the Code to Work with Cross Page postback:
The Following is the Code for Form1:
Here I'm using a LinkButton to go to 2nd Form.

<asp:LinkButton ID="LinkButton1" runat="server" PostBackUrl="~/CrossPagePostback_Form2.aspx">Go To Form2</asp:LinkButton>
        <br />
        <br />
        <asp:TextBox ID="txtTest" runat="server"></asp:TextBox>

Now in 2nd Form I'm just using a Label to Show the Value of TextBox present in 1st Form:

protected void Page_Load(object sender, EventArgs e)
    {
        if (PreviousPage != null)
        {
            TextBox txtTest = (TextBox)PreviousPage.FindControl("txtTest");
            Label1.Text = txtTest.Text;
        }
    }

This is the Process to access data present in Previous Page using CrossPage Postback.
For better Understanding of CrossPage postback you ca refer the following link:
Cross-Page Posting in ASP.NET Web Pages[^]

Regards.