restore a specific date's backup

@charlesxu_nj The Linode Backups service rotates out available Backups, meaning the one you you're referring no may not longer be available.

From our guide entitled The Linode Backup Service:

Backups are stored on a separate system in the same data center as your Linode. You can store four backups of your Linode, three of which are automatically generated and rotated:

• Daily backup: Automatically initiated daily within the backup window you select. Less than 24 hours old.
• Current week’s backup: Automatically initiated weekly within the backup window, on the day you select. Less than 7 days old.
• Last week’s backup: Automatically initiated weekly within the backup window, on the day you select. Between 8 and 14 days old.
• Manual Snapshot: A user-initiated snapshot that stays the same until another snapshot is initiated.

Important to note:

The daily and weekly backups are automatically erased when a new backup is performed. The Linode Backup Service does not keep automated backups older than 8 - 14 days.

In Classic Manager, you're presented with a log of successful Backups, including old Backups that are no longer available for use as a back that you can deploy from. That means that the Backup in which you're referring to may not be available.

Alternatively, if you've encountered a problem and are worried about new Backups overwriting good backups with bad data you should open a Support ticket. Support will be able to pause your Backups service, allowing you to keep the good backups until you've been able to recover.

I would also recommend using the Manual Snapshot whenever you're able to make changes on your Linode. The Manual Snapshot never expires. This could be extremely valuable in cases of needing to play the long game in determining how changes have affected your Linode.