If you receive a message from someone on Instagram asking you to reply to them, there are a few things you can do in order to do so. First, open the app and tap on the three lines in the top left corner of the screen. This will show you all of your followers and their messages. From here, you can tap on the one that interests you and select “Reply.” Once you have replied, your follower will be able to see that they have received a response and will be able to follow you back if they want to.