Answer:
"You have never heard of Bach?" he asked.
Step-by-step explanation:
you have
1. Capitalize the first word in the sentence
You have neaver heard of bach he asked.
2. Fix the spelling error
You have never heard of bach he asked.
3. Capitalize proper nouns
You have never heard of Bach he asked.
4. Add proper quotation formatting
"You have never heard of Bach?" he asked.