Hyper-V Virtual Network - No Network Access

Hello Team

As my host server and virtual running properly and suddenly its virtual server access got stopped working, once i check the server and and Virtual Adapter its says No Network Access. We nothing changed over the host as well as for virtual card (I was having Internal ). I tried to find out the issue but unable to do that. My host server is running properly with network and internet access.

But the VMS got stopped working due to its card says No Network Access-

Host Server:Windows Server 2008 R2 SP1

Please help my all the virtual machine not working due to its (More than 6 Virtual servers/machine hosted on this host server)

Thanks Ranveer Katiyar