The government has redundant system backups, they are not on a PC hard drive.
This same scenario happened during the second Clinton administration. Northrop Grumman was hired to retrieve all emails, especially those deleted, and did.
There are indeed backups and redundant systems, so this is just a smoke screen, a stalling tactic.
The administration’s goal is run out the clock on the public’s attention to the matter, and force Congress to spend money looking for the “lost” emails.