First off get or buy the horse at the whiterun stable, via console on PC, get the ID's horse, put the serial into a notepad file TXT, park your horse at the front door of whiterun city, then when you have such trouble, via console type this bat yourfilename.txt. If it doesn't work, then COC whiterun or COC riverwood and then again type in console bat yourfilename.txt to teleport you close to your horse location. it works mainly everywhere in the game, quests and events aren't broken or canceled. When you have to pass a door or a cavern access, it may helps a lot. Of course, you can do thr same with a companion ID.