Open Gmail
Use the search bar at the top
Type keywords, sender name, subject, or email address
Search for the email
Open the email if it appears in results
If needed, search for `in:all` plus your keywords
Search for `-in:spam -in:trash` to exclude spam and trash
Check the All Mail folder in the left menu
Scroll through All Mail to find archived messages
Use Gmail filters like `from:`, `to:`, `subject:`, or `has:attachment`
Open the archived email
Click Move to inbox if you want to restore it to the inbox