Try with this:
System.IO.DirectoryInfo info = new DirectoryInfo("c:\\");
int NumerSubDirs = info.GetDirectories().Length;
int NumFiles = info.GetFiles().Length;
FileInfo[] fileinfos = info.GetFiles();
float totalSize =0;
foreach (FileInfo infof in fileinfos)
{
totalSize += (infof.Length / 1024 / 1024);
}
Console.WriteLine("Number of subdirs -> " + NumerSubDirs.ToString());
Console.WriteLine("Numer of files -> " + NumFiles.ToString());
Console.Write("Size of files -> " + totalSize.ToString());