This happens quite frequently with me and often I will stumble across these paintings and struggle to remember what my thoughts were about them and sometimes have no recollection about what they are about.
The question is what to do with these paintings? sometimes I will paint them over with gesso and use the canvas to start again, occasionally the canvas has an image that can't be easily covered, these I reluctantly have to dispose of. The majority of these paintings I will attempt to continue with, although I find it extremely difficult to do so.
Why do I find it so hard to pick up where I left off? I believe it's because I am not an artist that paints an image or a scene, when I start a painting I invest time in thinking about the feel of the painting, the sense of place or the object that I am trying to convey, this becomes a story within me, an image tied to emotion and my experiences at that particular time and place. To come back at a later date and try to pick up the pieces is impossible, I am no longer that person, that emotion has changed, the experiences have grown. My only recourse is to reinvest time to take the painting to somewhere else, to reconnect to the new me in this new world, it might not survive the journey but it will be better than lying unfinished in a dusty corner of the studio.
Please let me know any thoughts and comments, it would be great to hear what other artists do with their old unfinished paintings.