I think you may have overfaced yourself & your horse. I would advise you to go back to basics & work on trot & canter poles to help rebuild you & your horses confidence. I have been through a similar thing & going back to the beginning & slowly building up to a jump really helped. I think its also a good idea to find a good instructor who you trust to help you both. It is always benifical to have a set of eyes on the ground telling you whats happening & what you need to do to to get better. It needs to be someone you trust & who understands you & your horses capabilities, so they will be able to encourge you to progress further but wont push you both too far. I trust my instructor completley & she never tells me to do anything she thinks is beyond mine or my horses capabilities. She has got me jumping 1metre jumps confidently, something I thought I would never do! It will take time but dont give up you will both get there! Good luck!!

Yes it does sound like you either over faced your horse or you were maybe slightly backing off him into the jump. I am going through exactly the same thing at the moment so i know how hard it is but i know i have to persevere to get back into jumping. My instructor has to do a lot of persuading before i'll even canter over a trotting pole raised half a foot off the ground! I would definitely start from the beginning with jumping for both you and your horse so you build your partnership and confidence back up and i'm sure you will be tackling 4ft fences again in no time!