มี ชุดตัวอักษร abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNOPQRSTUVWXYZ0123456789 พอกดปุ่มอยากสุ่มออกมา 25 ตัวอักษรอะครับ

Module Module1
    Sub Main()
        Dim KeyGen As RandomKeyGenerator
        Dim NumKeys As Integer
        Dim i_Keys As Integer
        Dim RandomKey As String

        ''' MODIFY THIS TO GET MORE KEYS    - LAITH - 27/07/2005 22:48:30 -

        NumKeys = 20

        KeyGen = New RandomKeyGenerator
        KeyGen.KeyLetters = "abcdefghijklmnopqrstuvwxyz"
        KeyGen.KeyNumbers = "0123456789"
        KeyGen.KeyChars = 12
        For i_Keys = 1 To NumKeys
            RandomKey = KeyGen.Generate()
            Console.WriteLine(RandomKey)
        Next
        Console.WriteLine("Press any key to exit...")
        Console.Read()
    End Sub
End Module

    class Program
    {
        static Random C = new Random();
        static void Main(string[] args)
        {
            for(int i=0; i<50; i++)
            Console.WriteLine(GenString(25));
            Console.ReadKey();
        }
        static String GenString(int numGen)
        {
         
            char[] myChar = {'0','1','2','3','4','5','6','7','8','9',
                            'a','b','c','d','e','f','g','h','i','j',
                            'k','l','m','n','o','p','q','r','s','t',
                            'u','v','w','x','y','z',
                            'A','B','C','D','E','F','G','H','I','J',
                            'T','S','R','Q','P','O','N','M','L','K',
                            'U','V','W','X','Y','Z',
                             };
            string ret = "";
         
            for (int i = 0; i < 25; i++)
                ret += myChar[C.Next(0, myChar.Length)];
            return ret;
        }
    }