My computer just went down

There appears to be no record of all the music I painstakingly wrote note by note (from the last few years).
Luckily I have printed most if it out, but now of course it's not on MUSETTE so I cannot edit it (change the key signature etc).
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ALso having had this nasty experience, is there any way of saving the music elsewhere on the computer
in a form that will stay there when the MUSETTE programme is removed and reinstalled?