To show the Map Network Drive button, follow the next steps:

1. Open the Registry Editor click on the Start button on your taskbar, then click on Run and type "regedit" and click on OK to start the regedit utility.
    
2. Expand HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advance (see picture 1).
   
   

   Picture 1

3. Set the value of "MapNetDrvBtn" to "1".
    
4. The modifications you made will be in effect after you logout or reboot your PC.