The last changes and more of them has been not saved

See How to recover a backup copy of a score, esp. the part about the automatic backups

To be clear: MuseScore works like other computer programs, in that you are expecting to save files yourself. It's a different model from how most mobile apps work, where work is often saved. So definitely, when using MuseScore or any other computer program, you need to be in the habit of saving your work explicitly via the Save command (in File menu, or main toolbar, or Ctrl+S standard shortcut). And when you first save the file, you need to choose a folder to save in and give the file a name.

Now, if you're saying you did save your work explicitly, then that work is definitely saved, to the exact same folder & filename you saved it to. If you are opening a file and not seeing your work, then presumably you are simply not opening the correct file - like you hare choosing one with a similar name but in a different folder, for instance. So you just need to remember the exact folder & file name you actually saved to and open that,

if you need further assistance finding the right copy of your file, please ask for help don't he support forum, and include more info such as your OS, the exact file and folder name you had believed you saved to, the last modification date shown on that file in your file browser, etc.