Where have you got them backed up? If you haven't, have a look in Google photos, hopefully at sometime you set it to do your backups for you automatically. Another option is if they are on an SD card you can put the card in a PC and retrieve them. Best of luck in retrieving them.
Welcome to Android Central! Since there's a decent chance the touchscreen still works, you could try unlocking the phone blindly, connecting the phone to your computer, changing the phone's USB connection mode to MTP (again, blindly), and then using Windows Explorer to copy the files over. See this post for some ideas: http://forums.androidcentral.com/ge...de-accessing-locked-phone-cracked-screen.html