I once had a similar corruption problem with NV1 and perhaps this might help. Maybe someone else has another recommendation.
I cannot recall the circumstances but the corruption became apparent only when I performed a certain operation and the books then became unusable.
I suppose we all have our back up strategies and some might say this is overkill but for the past twenty years or so, I have backed up NV in entirety each day to DVD (in the “old days” it was to CD and tape) and sometimes more than once. At the end of the month, I back up to DVD, a USB hard drive, and a flash drive. Except for the flash drive, the backups go back two years.
Of course, if data is corrupted, the corruption is also backed up.
However, I also export and add each day’s journal entries into two separate files, one a yearly file and one a current month file. This is done automatically with a procedure each time I exit.
When I discovered the corruption problem at the end of the month, I restored the previous day back up but found I had the same corruption. I went back one week, two weeks, etc., with the same problem.
I finally restored a backup from the middle of the previous month that proved good. I then went to my exported journal file and imported the needed journal entries to bring the books up to date.
As near as I can recall, the only thing I needed to do manually was to add any new accounts created since that last good backup and redo any reconciliations since that time.