I have the same problem too. I recently changed my network card from Wirless N-135 to AC7260 due to that I changed home network from 802.11n to 802.11ac. I have a MSI GE60 running Windows 7 64-bit. After sleep the card (AC7260) fails to restore wireless. It never happened with the old and slower N-135. Often whe the AC7260 fails after sleep there is a couple of logs in system log. Today no log but an exclamation mark in device manager, and a note that the device was stopped due to error. Solution was to uninstall the device without removing the drivers, and search for hardware change. A restart will also helps. My drivers are 17.1.0.19.
regards //Freddan