Maybe you should try upping your calories for a week or so, that might help. Depending on how many calories you're eating now, your body could be used to one particular level and be just poking along. I went up from 1,200 to 1,400 last week and lost 3.6 pounds. Even though it was kind of scary to eat more than I'm used to, with my amount of exercise I needed more fuel.
If you don't want to change how much you're eating, look at what you're eating. How many meals, are they three big ones or five spread out throughout the day? Are you foods whole or processed? Are you getting all of your nutrients (enough carbs, fat, and protein too)?
And if even that doesn't appeal try switching up your workouts. If you walk now, try a new video, use a different machine or take a class you've been meaning to take. To get your body out of a rut you need change things up.