How do I get my receipt from a physical Apple store purchase?

I bought Powerbeats 3 about 2 months ago in the Upper East Side Store and can’t find my receipt. I have checked everywhere. Can I just take them in to the store and get them repaired? The sound isn’t working should still be covered under the warranty. I looked everywhere in my emails, Apple store (even though it was purchased online), and “check your receipts” from forums reply to someone else. Thx