Here In this Path you mentioned test (Test is folder name which is there in 'D' drive) in this folder you will find 26-9-2014_1,26-9-2014_2 26-9-2014_3 folders
string path = @"D:\test";
DirectoryInfo di = new DirectoryInfo(path);
if (di.Exists)
{
string exp = DateTime.Now.ToString("dd-MM-yyyy") + "*";
string[] dirs = Directory.GetDirectories(path, exp + "*");
int count = dirs.Length;
Directory.CreateDirectory(path + "\\" + exp.TrimEnd('*') + "_" + (count + 1));
}