What would you say to any one of your friends that you neglected for an entire year? Treat your charachters like your friends. Even your nastiest of protagonists should have something about them that you like and want to keep around.
Write each one of your charachters a letter – totally unrelated to the novel/story – and tell them exactly what happened to you and what you want to have happen in the future. THEN write a reply from each of them and let them tell their side of the story. The secret to this second letter is to write, and just write with out thinking. Let THEM tell you what their reply is.
Some may welcome you back, some may not even reply and you will have to let them go. But that is ok, maybe they didn’t want to be there in the first place: a reason you could not write about them and looked for a boyfriend? In the long run you may at least discover how all of your charachters will react to abandonment, and maybe this will work into your writing? How do people react to abandonment? to forgiveness? to the future when clouded by a past? How do your charachters react to working through past problems? You will never know what they think or feel until you give them the voice to tell you.
Lots of luck!