Just syncing wouldn't do this. If you used Replace Online Library from a computer with an outdated Zotero library, that would do this, and you would have to do the same from a computer where you had an up-to-date library (possibly after restoring from an automatic backup, unless you're able to disable network access in order to temporarily disable auto-sync in the Zotero sync settings to prevent it from pulling down the deletions).

I'm not sure what you mean by "already restored the data", but if you're saying you restored from a backup, you would have whatever data you had at the time of the backup.