If you remember roughly when an attachment arrived, start with a date range and a file type. Gmail search can combine these conditions; you do not need to open every message or create a permanent sorting rule.
Build the query in stages
In Gmail on a computer, enter after:2026/09/01 before:2026/10/01 filename:pdf. This is an example for a September search, not a claim that the file exists in your account. Keep the year/month/day order. If the expected message is close to a date boundary, widen the range by a day and check its received date directly.
Add a remembered subject word with subject:minutes only after seeing the broader results. Gmail also supports has:attachment; filename:pdf is more specific when you need that file type. A Google Drive link is a different kind of item: try has:drive if the document was shared as a link rather than attached.
Remove assumptions before declaring it missing
If nothing appears, first remove the subject condition, then widen the dates. Check that you are searching the account that received the message. To include Spam and Trash, add in:anywhere; inspecting results does not restore or move those messages.
Open the actual matching message
Conversation view can group several emails together. Expand the relevant message and inspect its date, sender and attachment name before downloading. Save the required PDF with a recognisable name and check that it opens. Search results are a way to locate a candidate, not proof that every attachment in the conversation is the version you need.