C#

   [StructLayout(LayoutKind.Sequential)]
   private class NETRESOURCE
   {
    public Int32 dwScope;
    public Int32 dwType;
    public Int32 dwDisplayType;
    public Int32 dwUsage;
    public string lpLocalName;
    public string lpRemoteName;
    public string lpComment;
    public string lpProvider;
   }

[DllImport("mpr.dll")]
private static extern Int32 WNetAddConnection2 (
                                NETRESOURCE lpNetResource, 
                                [MarshalAs(UnmanagedType.LPTStr)] string lpPassword, 
                                [MarshalAs(UnmanagedType.LPTStr)] string lpUsername, 
                                Int32 dwFlags);
[DllImport("mpr.dll")]
private static extern Int32 WNetCancelConnection2 (
                                [MarshalAs(UnmanagedType.LPTStr)] string lpResourceName, 
                                [MarshalAs(UnmanagedType.Bool)] bool bForce);

void MapShareToDrive(string share, string, localdrive, string username, string password);
{
// Prepare for network access
NETRESOURCE netResource = new NETRESOURCE();
netResource.dwScope = 1;
netResource.dwType = 1;
netResource.lpLocalName = localdrive;
netResource.lpRemoteName = share;
// Connect to network share
int iRetVal = WNetAddConnection2(netResource, password, username, 0);
// You can also do the following to make the system prompt for username/password
// int iRetVal = WNetAddConnection2(netResource, "", "", 24);
if (iRetVal != 0)
{
  throw new System.IO.IOException("Failed to gain access to network share. Error code: " + iRetVal);
}
} 

public void MapDrive(char drive, string path)
{
  Process.Start("net.exe", string.Format("{0}: {1}", drive, path));
}