* He is captured by Death Eaters: Ollivander is taken prisoner by Bellatrix Lestrange and other Death Eaters, likely because of his knowledge of wandlore and his ability to identify wandmakers. He's kept in a secret location.
* He endures torture: We know Ollivander is tortured, likely to reveal information about the Elder Wand and its secrets.
* He is eventually rescued: Harry, Ron, and Hermione manage to free Ollivander from his captivity. This is mentioned in the final battle scene.
However, the specifics of his time in captivity and his escape are never fully explored in the books. We don't know how long he was held captive, how he was tortured, or who rescued him.
It's likely that the events of his imprisonment are meant to be a reflection of the larger conflict between good and evil, highlighting the cruelty of the Death Eaters and the resilience of those who oppose them.