Roku has been sending emails and notices for quite a while regarding the removal of DP channels. I doubt very much if there's any way to retrieve a deleted channel.
Your only option is to create a SceneGraph (SDK) channel that uses your DP feed file.
FREE Windows desktop software for converting Direct Publisher channels to SceneGraph (SDK), for creating
BIF (Trick Play) files,
Roku (MRSS, JSON) feed files, and
FireTV feed files @
GitHub/rrirower.