For Outlook.com, check these in order:
- Deleted Items
- Open Deleted Items and look for the missing August messages.
- If found, select them and choose Restore.
- If they are not there, in Deleted Items select Recover items deleted from this folder and restore any messages found.
- Messages removed from Deleted Items are recoverable for 30 days.
- Archive
- Open the Archive folder. Archived messages do not appear in Inbox.
- If found, select the message and choose Move to > Inbox.
- Junk Email
- Open Junk Email and check whether the messages were moved there.
- If found, select the message and choose Report > Not junk.
- Messages in Junk Email are automatically removed after 30 days and are not recoverable.
- Filter and Focused Inbox
- In the message list, select Filter and set it to All.
- If Focused Inbox is enabled, check the Other tab too.
- Rules
- Check whether an Inbox rule or Sweep rule is moving messages out of Inbox.
- Go to Rules settings and review any rule that moves or deletes mail.
- Recent sign-in activity
- If messages disappeared without any action, review recent sign-in activity for the Microsoft account to check for unusual access.
If the missing August mail is not in Deleted Items, Recover deleted items, Archive, or Junk Email, and more than 30 days have passed since deletion, the context does not provide a recovery method beyond those locations.
If the issue is only in the Outlook view and not actual deletion, a filter may be hiding items. In Outlook, open View > View Settings > Filter and review filters such as date received, read/unread, sender, or size.