If you have windows, you will need these drivers to use ADB or Fastboot with your Nexus 4. The long method of getting this is downloading the SDK and running it. I have extracted the drivers and put it into a rar file for easy use.

Follow these steps if you haven't plugged your phone into your computer before.
1. Download the file.
2. Extra the files into a folder.
3. Plug your phone in.
4. When prompted, select "Let me pick from a list of device drivers on my computer", NOT "browse for driver software on your computer".
5. Then you have to select "have disk" and then point to where you extracted the drivers (the usb_driver folder) to install the drivers.

If you already installed other drivers and they don't work for you. Download the drivers below and follow these steps:
1. Enable USB Debugging on your phone.
2. Plug your phone into your computer.
3. Go to Device Manager on your computer and locate your device. It will either be under "Android Devices" or "Other Devices" depending whether drivers have been installed or not.
4. Right click on your phone and select "Uninstall."
5. In the box that appears, check the option to "Delete the driver software for this device" then proceed.
6. When that is done, go back to Device Manager and refresh.
7. Locate your phone and right click to select "Update Driver Software."
8. When prompted, select "Let me pick from a list of device drivers on my computer", NOT "browse for driver software on your computer".
9. Then you have to select "have disk" and then point to where you extracted the drivers (the usb_driver folder) to install the drivers.
10. Unplug your phone and restart your computer.
11. Plug it back in and everything should work