I've seen a number of similar questions but no solutions to my problem.
Windows 7 Home Premium - 64bit
Realtek WLAN driver
After resuming from a sleep, the network adapter dissappeared. This happened before and they replaced the computer, after trying a system restore and then full recovery. Apparently, it's not the computer.
The Wireless adapter is missing from device manager, much less the network and connections area. In troubleshoot, the computer simply says a network cable needs to be plugged in. There is no wireless choice under network connections. There is no wireless
adapter tab upon right click of Network Adapter in Device Manager.
The Realtek WLAN driver DOES appear in the Programs & Features list. I uninstalled, reinstalled, and also found/installed a patch for the driver. This did not work. I also started/automated the Autoconfig scripts for wireless. Nothing works.
This just happened to me and I was able to get past it by doing several hard reboots. I had to fully charge the battery , and after three attempts with increasing intervals of time, the system appearently turned the wireless adapter back on.
After the card reappeared, I was able to find it in device manager again, in my case Intel(R) Centrino(R) Wireless-N 2200 under network adapters . Then a right click, to properties , within properties you chose power Management tab. There you will probably
discover that by default the computer is allowed to turn off this device to save power. Uncheck the box , click ok and reboot . Hopefully this will prevent it from happening again.