Make sure if you're using a seperate code source (code behind page) that the references and paths are correct. I know the first time I uploaded my asp.net project, I forgot to upload my code source pages and had similar issues. Maybe your references aren't correct...did you change or move files around in your directory structure? For instance, if my home.aspx page is in the same directory as my home.aspx.cs page, they should have a reference as below...did you by chance move them to another directory without changing the references?
<%@ Page Language="C#" MasterPageFile="~/MasterPage.master" AutoEventWireup="false" CodeFile="home.aspx.cs" Inherits="Home" Title="Your Title %>
If you had moved home.aspx to say /content_files/home.aspx then your code reference should reflect the same.