Oh man, that's a special kind of pain. I lost my list once and trying to remember what you've seen is the worst part. Maybe try a site like Anilist next time so it's saved online.
My old laptop died with my first 200-title list, so I feel that pain! Wendy674 is right about online backups, but I still keep a local copy just in case.
Honestly that "just in case" local copy is the real move. Tbh I've seen too many online services just shut down or change their rules. My friend lost years of game saves when a cloud service went under. So yeah, always keep your own backup on a hard drive or something. It's the only way to really sleep easy.