"Who broke the glass?" is (most likely) the correct answer you are looking for. However, it is possible to imagine a context in which the other sentence: "Who did break the glass?" is OK too: - Do you remember that family party years ago when somebody broke that valuable wine glass - and mum and dad got so angry? - Oh yes, I had forgotten that. Actually, who DID break the glass? - Well, don't tell anybody, but it was me!.. (You would put the stress on the word "did" here...)

This is a good question and the issue is determined by whether the noun is the Object or the Subject of the sentence. 2 examples: 1. Who phoned you last night? (Who is the subject of the question - no need to use “did”. 2. Who did you phone last night? (Who is the object of this question, so we need to use “did” here. Feel free to ask further if you need to

Charlie gave a great answer.

Who did break the glass .

They're both correct.