It is important to back up your Zotero library regularly. To back up your library, you can save the entire Zotero folder to the cloud or an external device. Locate the folder by clicking Edit → Preferences → Advanced. Under the tab Files and Folders you will find the button Show Data Directory which will allow you to locate the folder on your computer.
Read more on how to back up or restore your Zotero library.
It is important to back up your Zotero library regularly. To back up your library, you can save the entire Zotero folder to the cloud or an external device. Locate the folder by clicking Preferences → Advanced. Under the tab Files and Folders you will find the button Show Data Directory which will allow you to locate the folder on your computer.