lost to the world

Short definition from Wiktionary

Adjective

1. 1
   No longer used or available; unknown to or forgotten by everyone.
2. 2
   No longer existent, deceased.
3. 3
   Physically located in a remote place where one is unnoticed or incommunicado.
4. 4
   Mentally focussed on one's own thoughts or feelings, or on some task, to such a degree that one is unaware of other people or of one's surroundings; unconscious.