Backup

There are a number of things that you can try. I don't know what operating system you use, so these instructions will be geared towards Windows users.

• First, unless you've permanently deleted the file, it will be recoverable from the Recycle Bin.
• Musescore creates backups that you can try to locate.
• If you make regular backups of your system, you might find (an older version of) your file there. Utilities such as OneDrive may create automatic backups for you.
• If none of those methods work, you can try file recovery software, for example the one provided by Microsoft.