Is it because you dont want to talk or is it because you dont want to tell the class about yourself?
If it is the first one then face your fear. It wont be as bad as you think and the more you do it the easier it will get. I promise.
If its the second one, bend the truth a lot. Or, focus on a couple of things that you dont mind sharing. Even the person who has lived an awful life can find okay things about their life. For example, someone who was in foster care may not want to say what there situation is, so they could just say 'my mum and dad are...'. They can leave out the finer detail that it isnt their real mum and dad. Just like someone with divorced parents wouldnt have to say there parents dont live together, they can just leave that fact out. Mention some of your favourite things. If you dont want to mention your real favourite things (like I dont go shouting about the fact that I write) then just mention things you like, or make it up. 'My favourite animal is a dolphin' etc. It would be quite easy to get hold of a picture of a dolphin.
Pick a situation/ event/ or day out that you could talk about. You must be able to find something - even if its like a birthday party from when you were four. Talk about that.
The beauty of talking about yourself is there is so much about you. Even if you get up and talk about your apperence. 'My name is...., im .... years old, i have brown hair and brown eyes' you are still doing what you are being asked and wont get an F. There are ways around doing things we dont want to.
If you need some more help drop me a message
Two hearts, one passion. Because you are my saving Grace