I guess it depends what you hate about your body and face as to how to deal with it. If it's because you're over or underweight, the obvious solution would be to change your weight. If it's something else, then there's always plastic surgery or similar to make a change but to be honest, it may be better if you could go back to accepting yourself the way you are. I'm sure you are just perfect, even if you don't see it. If you are having thoughts of hurting yourself, or doing something drastic to fix your appearance, please see a doctor as you may be suffering from Body Dysmorphic Disorder.
Hi, it sounds like you might have gone through a change or some sort of event that caused you to look at yourself differently. You said you used to accept yourself but it is not the case anymore. Perhaps you should try to answer what is different now and why you are looking at yourself differently suddenly. It may not be the way you look but just the way you think about it.
Put yourself in somebody else's shoes (preferably somebody that you love), and ask yourself the same questions you do to yourself that make you feel bad. You would never say things about somebody you love that would make them feel terrible, and you overlook their flaws like they're no big deal. Sometimes, you have to look at yourself like an outsider.
What has changed between you accepting yourself and you now hating your body and face? Knowing what triggered the change in the way you see yourself might help you find your way forward. You could try to find one small thing about yourself that you do like, no matter how small. Perhaps you like your eye color, your teeth, maybe you have nice hands or feet, perhaps you are rocking your brows or your having a great hair day. If you can learn to love even the smallest part of yourself it's a step towards accepting yourself as a whole.