Navigate to your Z: drive or Department network drive in File explorer, then open the shared folder the document is located in.
Right-click the file > Show more options > View in cloud
Authenticate if prompted to.
Once the document opens in the browser, at top left, click the back arrow so that you can see the document listed view.
Check the square next to the document and on the right side you should see a list of options, one of them should be “Versions & History”, this is where you can restore to a previous version and make it current.