I was composing an edude for piano on this ap,i wrote like 3 pages than suddenly musescore crashed and i lost my work,i dont remember it and i didnt get the chanse to save it earlier

While writing 3 pages you didn't get the chance to save in between???

Still MuseScore does autosave every 5 minutes (unless you changed that), so there might be something left

If you have never saved that score - and meanwhile you did not start a new score - the score will be in a file 'new_project.mscz' , in:
Windows: %LOCALAPPDATA%\MuseScore\MuseScore4\
Mac OS X: ~/Library/Application Support/MuseScore/MuseScore4/
Linux: ~/.local/share/MuseScore/MuseScore4/