Approximately 300 citations were collected in ZoteroBib over the past year and just disappeared. Please advise if there is a way to recover the citations. Thank you.
ZoteroBib really isn't intended for long-term storage of items — you should use Zotero for that. If you're using ZoteroBib for a longer period, you absolutely would want to be regularly using "Link to this version" to store copies online that could later be retrieved.
No, probably not, I'm afraid. If you didn't use "Link to this version", the data is just stored using your browser's local storage, which isn't really intended to be accessed externally. If you had a full backup of your computer, it's possible you (or someone) would be able to extract the data from the right files, but even then it might be difficult.
Upgrade Storage
More details here:
https://zbib.org/faq#where-is-my-bibliography-stored
https://zbib.org/faq#how-long-is-my-bibliography-stored