From your picture it appears the digitizer is still attached to the LCD. The display(glass, digitizer, and LCD) assembly separated from the frame it is adhered to, which the LCD shield screws into. Just remove the two screws from the bottom of the phone and try taking a pry tool to pry the frame up to be able to access the connections on the motherboard. Then if the display is in working condition you could re-adhere it to the frame with some adhesive or replace the whole display if there is another issues with your current display besides it separating from the frame. Beware of the home button cable when prying the frame up. Make sure to disconnect the home button cable before fully lifting the frame out to avoid tearing the cable.