How do I retrive deleted pictures from my LG phone?

There should be a memory card or stick insides your LG phone, take it out and load it on a card reader and then insert it to a computer that has installed a photo recovery program. Try this one (it seems free):

http://www.datarescuetools.com/photo-recovery.html

But there is one thing you should remember - before the photos are recovered from your LG, it is recommended not to take more photos or save more files to the phone mass memory as this may cause your original data overwritten. Once overwritten, it is almost impossible to recover. Just bear this in mind.