•  Open any internet browser or the Reddit app and go to Reddit.com.
• Type the exact username of the person you're looking for into the search bar at the top of the homepage, and search.
• Look for the heading 'Communities' or 'Communities and Users' on the results page. A list of persons and subreddits that match your search will appear beneath it. You'll want to seek for one that begins with 'u/' and then the username you're looking for. You'll look for u/JohnDoe if you're seeking for a JohnDoe.
• To view their profile, click on their name. You can view their comment and thread history, as well as send them a message, from this page.

Read More: How do I find someone's Reddit account knowing the email address?