//calculate code
public static string CalMd5Hash(string input)
    {
        MD5 md5 = MD5.Create();
        byte[] inputBytes = Encoding.ASCII.GetBytes(input);
        byte[] hash = md5.ComputeHash(inputBytes);

        StringBuilder sBuilder = new StringBuilder();

        for (int i = 0; i < hash.Length; i++)
        { sBuilder.Append(hash[i].ToString("x2")); }
        return sBuilder.ToString();

    }
    //verify
    private static bool VerifyMd5Hash(string input, string hash)
    {
        string hashOfInput = CalMd5Hash(input);
        StringComparer comparer = StringComparer.OrdinalIgnoreCase;
        if (0 == comparer.Compare(hashOfInput, hash))
        { return true; }
        else { return false; }
    }

SqlDataReader dr = Function.GetData("Select * from tblUsers where Username='" + username.Value + "' AND Password='" + password.Value + "'");