Data is not saving in SharePoint

I recently created an e-commerce website that sells iPhone back https://justelegance.de/collections/iphone-12-hullen . Yesterday, I spent several hours researching my competitors' SEO strategies and keywords, and recorded the information in a SharePoint file. However, today when I opened the file, all the data was missing. I am very concerned and wondering if there is any way to retrieve the lost information or if there are any other solutions that could help me. Thank you in advance for any assistance.