C# ASP.NET Webforms: TextBox(Not Textbox.Text) is coming out null. How do you fix this?

I am testing out a webform to save strings from a textbox. The program stops running when I press a button programmed to save the info into an array. Here's the error:

System.NullReferenceException occurred HResult=0x80004003 Message=Object reference not set to an instance of an object. Source=TS_Webform StackTrace: at TS_Webform.Forms.Login.registerUser() in C:\Users\k20\Source\Repos\TS_Webform\TS_Webform\Forms\Login.aspx.cs:line 105 at TS_Webform.Forms.Register2.Button1_Click(Object sender, EventArgs e) in C:\Users\k20\Source\Repos\TS_Webform\TS_Webform\Forms\Register2.aspx.cs:line 25

heres the method that it the message directs me to:

   public static void registerUser()
   {
        User newUser = new User();
        Register2 register2 = new Register2();
        newUser.strName = register2.TextBox1.Text;//Stops here 
        newUser.strPW = register2.TextBox2.Text;
        //newUser.strEmail = textBox3.Text;
        newUser.strPhone = register2.TextBox3.Text;
        newUser.strHas = register2.TextBox4.Text;
        newUser.strNeeds = register2.TextBox5.Text;
        userArray[I(userArray)] = newUser;
   }

I tried numerous things like changing the Textbox-declaration line on Register2.aspx.designer.cs from protected to public and public static and neither has worked.

This sort of thing can happen when your code behind gets out of sync with your web form markup. For every control that is in your markup, there is supposed to be a protected member in the code behind class; if they do not match up properly, you can get an orphaned control, or the member can return null.

The simplest way to fix this is to completely delete the control (from both markup and code behind) and add it again using the form designer.