You need to go into the gallery app you are using and change the settings within that app to look for the images on the card rather than the phone.
Should it not work, then you may want to try a different app for the photos, or to move them back to the phone you have a couple options. First you can using the phone's file manager app (if it doesn't have one you can install one) to locate the files and move them back to the phone. Or you can connect the phone to a computer via USB cord and access the files through the computer and move them all from the card to the phone.