To import both RAW files and jpgs associated with RAW files as separate files, go to Edit, Preferences, General and tick the box next to Treat JPEG files next to raw files as separate photos
Setting LR back to it's default settings may be more complicated. You can go through preferences selecting in General, Reset all warning dialogs, in Presets, Reset all default Develop settings and the clicking on Restore Export presets and all the rest in that dialog. Or for a full reset you can delete your preferences file itself, the location of which is listed in the FAQ page here.
Make sure you understand LR well enough to know how this may effect your work, ensure you copy the preferences file somewhere else before deleting it so you can always replace it and ensure your catalog itself is backed up before making any changes.