I have a setup with a Windows 2012 server configured as a NAS for my VMWare servers (it's all free equipment, so I do what I can with it). If I'm ever doing maintenance where I have to take down the Windows NAS and the ESX boxes together, the NAS never reconnects automatically. I've left it for hours and it just won't connect.
Diztorted's suggestion worked perfectly for me. The NAS reconnected immediately and was accessible as it should be. I'm not entirely sure why it isn't reconnecting by itself, but I'm completely happy with this workaround, especially since I don't restart the system often. 