Data copied his positronic patterns over B4's and basically did a "Remember". When Picard is leaving B4 after their talk, B4 begins to sing "Blue Skies". I believe that this was intentional as a device to bring Data back, if needed.
So - Geordi and Wesley and Dr. Crusher work hard re-enforcing neural patterns and synaptic pathways, then the Holo-thearpy begins and B4 re-lives Data's recorded life (at high speed of course - android speed.) emerging from the experience as Data.
OR - The Ent-E makes a dash for Sigma Draconis 6, where Crusher puts-on the Teacher and restores Data's positronic patterns as thoght she were kniting - Child's play!
OR - B4 takes a job in the mess as cook and "Morale Officer".
So - Geordi and Wesley and Dr. Crusher work hard re-enforcing neural patterns and synaptic pathways, then the Holo-thearpy begins and B4 re-lives Data's recorded life (at high speed of course - android speed.) emerging from the experience as Data.
OR - The Ent-E makes a dash for Sigma Draconis 6, where Crusher puts-on the Teacher and restores Data's positronic patterns as thoght she were kniting - Child's play!
OR - B4 takes a job in the mess as cook and "Morale Officer".