Hi, this is very unfortunate. Would you next time also be able to link to the reported issue? The information you provide is at the moment too little to provide support.
Although I can guess what is wrong; you have made a backup of the extension folder and not of the browser folder. The information of this extension is stored in the browsers' localstorage database. Due to some unfortunate events, the browser can decide to clear its cache and cookie storage and you would loose your data.
Please describe the steps that led to the lose of data and perhaps even report this to the browser vendor.
For this reason, the application has an export function in 'Settings'. Always keep a physical copy of your secrets in a safe place. I am sorry, but I can not help you any further.