You need have + the Past Participle.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
Fefita DelDid they replied to you?You can't use this one. After a form of auxiliary do (do, does, did), you must use the plain form of the verb.
Fefita DelDid they reply to you?Correct.
Fefita Del Thank you, now i am going to study auxiliary verbsFirst of all, look at your sentence. I see four mistakes here.
Fefita Del Thank you, now i am going to study auxiliary verbsGood! I hope you won't be disappointed. There aren't a lot of auxiliary verbs to study.