You can re-download P.T. at your own risk
Here's a way to get P.T. back onto your PS4
P.T., the playable teaser for the canceled Silent Hills game, can be redownloaded using a method discovered by a member of the Gamexeon forum, but it will only work for those who downloaded the game originally when it was on the PlayStation Store.
Konami canceled Silent Hills back in April. Silent Hills was a collaboration between Kojima and Guillermo del Toro, starring The Walking Dead's Norman Reedus as the protagonist. In May, P.T. was removed entirely from the PlayStation Store, with no way to re-download the game. Since then, and as recent as October, those involved with the Silent Hills project has spoken up about the game's cancellation. Guillermo del Toro even said that the cancellation by Konami "makes no f*cking sense at all."
NOTE: We are not saying you should use the following method of getting P.T. back onto your PlayStation 4. Though there have been no posts about the method bricking consoles or getting them banned on PlayStation Network, the risk is entirely yours.
The video below will show you have to re-download P.T.. Essentially, you download the PC program 'Squid' and access your PS4 game library through a proxy server. Once there, you'll find your old download for P.T.. For the full step-by-step process written, visit gamexeon.