Almost two months after they were mysteriously pulled from Google's online repository of Nexus factory images, the Nexus 4 stock images have reappeared on the site. These are full copies of the stock Nexus 4 Android 4.2.1 firmware which can be used to reset the device back to factory software if anything goes wrong.
The file's MD5 hash is the same as the earlier image, so it looks like nothing's changed. And obviously, it's the same version of Android running on just about every Nexus 4 at the moment -- Android 4.2.1, build JOP40D. Interestingly, the Nexus 4 hardware binaries required to build AOSP for the device are still missing from the Google Developers site.
In any case, if you want to grab the Nexus 4 factory image you can once again do so at the source link.