Nexus 4 – Fix USB driver
Sometimes your drivers go wonky for some reason. Therefore, you cannot develop, debug or backup your content. Time to fix this!
Your Nexus 4 is not recognized anymore as an ADB device in windows 7.
Remove and install the driver for the device. Follow the steps as described by Google Android pages. They sometimes are somewhat confusing, so here is the right way to follow them.
Get the official Google USB drivers here:
OR get the specific OEM drivers of your device (LGE for the Nexus 4)
Install using the procedure as shown here: