Strange characters after submitting a form

Hi,
I have a form where I type greek characters and after submitting it, it turns them into words of characters '?' and some other characters in english,according to each greek character .For example, if I type "Ã?Å¡Ã?±Ïâ??Ã?¿Ã?¹Ã?ºÃ?¯Ã?±", it takes it as "?at????a"
These values are then stored wrongly in database.The aspx file is the following:
 
<%@ Control Language="C#" AutoEventWireup="true" CodeFile="CtrlHandleProjects.ascx.cs" Inherits="Admin_CtrlHandleProjects" %>
<table style="position: static">
<tr&g ...