pare-, pari-, pear-

1. To pass out of sight; to vanish.
2. To cease to exist; that which can not be seen nor found.
3. To get lost; especially, without a warning or an explanation: "Her son disappeared without a trace."
4. To cease to be seen; that is, by moving away or going behind or into something.

An instance when someone you want to talk to is impossible to find.

After death the heir apparent becomes the heir-at-law.

1. A system by which a permanent theater company presents a set of works during a season, usually in its own theater: "A repertory company is a group of actors and actresses who perform plays for just a few weeks at a time."
2. In medical homeopathy, an extensive reference book or computer program that lists and cross-references precise symptoms and remedies for those symptoms.
3. Etymology: "index, list, catalogue", from Late Latin repertorium, "inventory, list"; from Latin repertus, reperire, "to find, to get, to invent"; from re-, "again" + parire, a form of paerere, "to produce, to bring forth".