help me to generate a string randamlly

Will a GUID work for you?
It is easy as
System.Guid.NewGuid.ToString()

Cheers!

This will generate strings of random characters, 10 characters in length.  65 is the ASCII for A..65+26 for Z.

string s = "";

int n;

char c;

Random r = new Random();

for (int i = 0; i < 10; i++)

{

  n = r.Next(65, 65 + 26);

  c = System.Convert.ToChar(n);

  s = s + c;

}

//listBox1.Items.Add(s);