What happens if I flash an Android 4.4.4 system.img?

I recently wanted to update my Nexus 4 to Android 5.0 but I wasn't able to because I have apparently changed something in my build.prop file, so OTA updating doesn't work. If I flash a clean Android 4.4.4 system.img will it fix this problem and will it wipe any important files? Thanks in advance. :D