I don't understand why, but some of my AS-level students seem to have taken against me. They are really not the easiest bunch to teach, and I don't like many of them. I've been shouting at them a lot and have been on the edge of tears several times. I dread teaching this group, and even took a "sickie" to avoid them recently. I really don't know how to turn things around.
Liking or not liking students is a problem, and can lead to poor teaching.
You must try to be objective. Strange as it may seem, they may actually crave your "friendship" or "leadership" more than you realise. As teachers, we spend too much time looking for poor behaviour and getting wound up by it.
Good behaviour happens every day in classrooms, but we expect it, so we rarely pay any attention to it. Praising good behaviour might motivate others to act similarly. If students are working quietly, say something positive, rather than just barking at the student who's texting his girlfriend. This approach, rather than censure, may motivate more challenging students to contribute more productively.
Standing at the door and greeting your pupils in a friendly (but not informal) way helps to build a good teacher-student relationship. If this ends up with one or two of them calling you by your first name or offering a "high-five", then you should gently assert that this is inappropriate.
This approach could help them to like you and, more importantly, to feel comfortable - an ideal state of mind for learning.