We'd need more information on how your computer was repaired. If it was wiped clean and everything re-installed then whatever backups you made yourself and what you see on zotero.org is all you can get back. If they just created a fresh account for you, then your old Zotero database may still be there. https://www.zotero.org/support/zotero_data lists the default locations of Zotero data directories. You can also search your computer for zotero.sqlite files. Anything at ~ 1MB is an empty database. Look at the Modified timestamp to determine how recent that database is. Let us know if you find something.