Forest of Memory by Mary Robinette Kowal

Katya is an Authenticities and Antiquities dealer in the far future where the details of life are recorded on Captures. She collects items before this time for their nostalgic value, ordinary things like typewriters and dictionaries. 

She relies on her A.I. like many would really one a friend. That is why she find herself so unaccountably alone when her A.I. goes off-line.

Most of the novelette is Katya's experience of being kidnapped for three days by a strange masked man. He shows no empathy toward her during the three days she is "off line," but mysteriously he allows her to live to tell her tale.

This is one of the stories that leaves readers hunger for more, yet Kowal keeps some things shrouded in mystery.

This is a captivating SF/fantasy tale about how we construct memories and how we survive is both puzzling and thought-provoking.