I was using Windows 8 when I encountered this problem. My laptop's WiFi detects all WiFi networks but does not detect my office's WiFi. I am in range and my phone and colleague's laptops are connected to this network without any issue. I used to connect to this network before this issue occured. My laptop's WiFi can see other networks and can connect with them properly.
To resolve this issue I tried these things.
From 'Device Manager' uninstalled the WiFi adapter's driver and re-installed WiFi drivers I have downloaded from HP site. I am using HP laptop Pavilion g6 2207-tx. No luck.
Re-stared PC. No Luck.
Installed another Windows 8 O.S. on another partition(after formatting the partition) of the Hard Disk. This time I was stuck to see that in installation process Windows 8 installation program asks me to join a WiFi network when the installation was just about to finish. Same thing happened here too, except my office's WiFi I was able to see other WiFi networks. (I am still surprising from where Windows 8 installation program picked the WiFi driver?). BTW I skipped that process of joining WiFi and completed installation of Windows 8. Same situation.
I guessed that Windows 8 installation might have picked driver from the original Windows 8 installed on another disk partition. So this time I installed Windows 8 again. But in installation procedure I have deleted all the partitions and re-created new fresh partitions. Installed the OS on one of new partition. But No Luck(Also WiFi driver was surprisingly there. Installation procedure asked me to join a WiFi network but missing my desired network).
Now I guessed WiFi driver was in windows 8 disk image. So I installed Windows 7 this time (Also deleted and created fresh disk partitions). After successful installation of windows 7 I installed WiFi driver. It is working but office's WiFi network is still not shown but others are.
I have renamed my Office's WiFi.but still I can't see on my laptop. But changed name is visible on all other devices. Some one on web suggested this.