In order to convert MuseScore backups (.mscz,) to LilyPond music scores (.ly), you would first need to recover the backup using MuseScore and then proceed to export the file to LY format. There does not appear to be alternative for this conversion and your only hope is the default software.
Convert MuseScore music score backup to LilyPond music score file.
We found one software available in the database for this conversion.
Microsoft Windows software - convert mscz, to ly on Windows
A free cross-platform WYSIWYG music notation software
Convert from mscz, file format
|Yes, MuseScore supports mscz, file conversion as a source file type.||Yes||Yes||mscz, editor||Yes||No||No||No|
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.