From your query it is clear that, there is no row in your reader
If you want to use reader, then use the following code .
using (SqlConnection con = new SqlConnection(str))
{
con.Open();
SqlCommand cmd = new SqlCommand("select * from Registration where Email='" + loginemail + "' and password='" + loginpassword + "'", con);
using (SqlDataReader dr = cmd.ExecuteReader())
{
if (dr.HasRows && dr.Read())
{
Response.Write("Login Successful");
Response.Redirect("Home.aspx");
}
else
{
Response.Write("Wrong user name and password");
}
}
}
Check your reader has row or not
Check whether you have the data in table or not