can you please try to modified your code
SqlCommand comm1 = new SqlCommand("exec SaveBusinessChanges @Business_Name,@Address_Line_1,@Address_Line_2,@Address_Line_3,@County,@Provence,@Telephone,@Username,@PasswordNew,@Email", connWrite);
with this and try again...
SqlCommand comm1 = new SqlCommand("SaveBusinessChanges",connWrite);
also do one thing, you have used where cause in your Update statement, can you write simple select query with that where case and check it will return any data or not?
you need to uncomment your line of code which will actually going to execute your store procedure so please modified your code like this....
connWrite.Open();
comm1.CommandType = CommandType.StoredProcedure;
comm1.Parameters.Clear();
comm1.Parameters.AddWithValue("@Business_Name", txtChangeBusinessName.Text);
comm1.Parameters.AddWithValue("@Email", txtChangeBusinessEmail.Text);
comm1.Parameters.AddWithValue("@Telephone", txtChangeBusinessTelephone.Text);
comm1.Parameters.AddWithValue("@Address_Line_1", txtChangeBusinessAddress.Text);
comm1.Parameters.AddWithValue("@Address_Line_2", txtChangeBusinessAddress2.Text);
comm1.Parameters.AddWithValue("@Address_Line_3", txtChangeBusinessAddress3.Text);
comm1.Parameters.AddWithValue("@Provence", DDLProvince.Text);
comm1.Parameters.AddWithValue("@County", DDLCounty.Text);
comm1.Parameters.AddWithValue("@Username", Session["User"]);
comm1.Parameters.AddWithValue("@PasswordNew", txtChangeBusinessPassword.Text);
comm1.ExecuteNonQuery();
connWrite.Close();