I'm having trouble importing my photos into lightroom from my hardrive

Hi i hope somebody can help me out ,when i import and edit in lightroom and then put them on my portable hardrive , if i go back later and try and import them back to lightroom the only photos that i can work on are the ones i've worked on already , the rest of the photos in the same file wont import into lightroom , i hope i'm explaining myself properly , if anyone can help me out i'd be very gratefull , i think i must be importing them wrong in the first place