How can I reset my device without losing images on it? I know I can backup and restore. But I just don't want the images to be deleted (either phone memory or sd card). Meaning, have the folder of the images remain, so that Gallery can read all the images from it after reset. 

I want to reset because after an upgrade to Lollipop, com.android.phone doesn't work. So I tried several options, but could not solve this, so now I'm looking to reset
Factory reset does NOT erase any user data. It just erases system/data/data folder and cache. This is the reason why sometimes problems doesn't get fix after all: Because is not so low level as we'd like.