How do I recover my photos after factory reseting my lg phone?

My suggestion is that you can try Android data recovery tool. Before that, stop using your lg phone in case of data overwritten. Then link it to pc via usb cable, start the tool. The tool will scan out all data on your lg phone. If the photos can be scanned out, you can get the back.

I suggest you stop using your phone before you get all your photos back, which can avoid data overwritten. Then you need an Android data recovery, such as Bitwar Data Recovery, recuva, etc. to restore your photos. Android data recovery is not difficult to preform.