I came upon a situation where my Google Nexus 7 Tablet could not be detected by my Windows OS.
I tried to check if Google USB Driver was installed. It was but still the problem persisted. I tried some other windows USB related drivers to no avail.
However, this one ruled them all. Download the ADB Driver Installer. It should work with most, if not all Android devices.
If one of the device’s driver got corrupted, this installer will fix it for you.
Go to this link to download it: http://adbdriver.com/