i have hexa decimal(FFF8F4909a95).

If you're saying that each pair of hex digits represents an (extended) ASCII character in some code page, then try this:

using System;

class Test

{

static void Main()

{

string hex = "FFF8F4909a95";

string ascii = HexToAscii(hex);

Console.WriteLine(ascii); // may not display correctly depending on code page in use

Console.ReadKey();

}

static string HexToAscii(string hex)

{

string ascii = "";

for(int i = 0; i < hex.Length; i += 2)

{

ascii += ((char)Convert.ToInt32(hex.Substring(i, 2), 16)).ToString();

}

return ascii;

}