you can use to after answer. If you rephrase it like this. "Can somebody please give an answer to my question, please"

You can say "Can someone give me an answer to my question." In this sentence "answer" is a noun so you can use "to" after. Also for example you can "add water to something." (Water being a noun in this sentence again). But in your sentence "can somebody answer my question?" you can't add "to" after the answer, because it's a verb -"to answer." It's the same with the sentence "I water my plants." "To water" is a verb, so you don't add another "to". So you wouldn't say "I water to my plants." I hope this makes sense. If you have more questions, feel free to get in touch with me :)