Don't worry, go to BBK official website, find your model, and then find the download on the webpage. LoOK for the upgrade package of your model on the download page (it should be the same as the version of your learning machine, and your parents will scold you for changing to another version), and then follow the software prompts, and it will be ok in about half an hour. I suggest you don't do it yourself, although it won't be bad, it's very troublesome. You'd better go to the after-sales point. Although you have deleted the book function, you can still use it. Enter resource management, find the TXT file to open, and touch Open.