• Telegramusers will be able to designate chats as read or unread in the near future. Apart from being able to pin/unpin messages, which is one of our favourite Telegram features because We use it all the time, it has always worried me that there is no way to 'unread' a message so that the notification that prompts me to return to that particular chat is retained.
• Simply long-press the conversation that contains the message you wish to keep unread and choose 'Mark as unread' from the menu that appears. 

Read More: How can I back up my chats?