Well, once the file has been overwritten it cannot be recovered anymore. You should
always use the
auto save and backup options to prevent data loss. However, there's a chance your system made a shadow copy of (an older version of) the file, which you can verify by choosing "restore an older version" or similar in the context menu of the file in Explorer.
To prevent such issues from happening again in the future, I would appreciate if you could provide the crash dump OpenMPT created. It can be found in %TEMP%\OpenMPT Crash files. Just compress the mptrack.dmp file and post it here.
PS: The development corner is only for source-related questions - not for questions regarding the program or bug reports.