Open Gmail
Click the search bar at the top
Search for the email using sender, subject, or keywords
Open the email if it appears in search results
Click the More icon if needed
Select Move to Inbox
Or open the All Mail folder from the left menu
Find the archived email in All Mail
Open the email
Click Move to Inbox
On mobile, open the Gmail app
Tap the menu icon
Select All Mail
Find and open the archived email
Tap the three-dot menu
Select Move to Inbox