Data loss, no known reason

Just to reenforce the importance of backups.
This morning I opened up Manager, opened the account I had been working on yesterday and “presto” all the bank info for the previous year had gone. YES vanished! disaster, all the EOY journale had gone, but there was still the bank info for the next year!!. Bit scarey,
So I restored the last backup - no use. Same as the present info. Luckily, I was able to recover a previous backup from the recycle bin. I have no idea what happened, and would love to know what went wrong so it doesn’t happen again. In the meantime, I will keep at least five backups before discarding them just in case.
Any suggestions or advice would be most welcome.
Peter

What if you search for all *.manager files on your disk? Perhaps you have two directories which contain data. And somehow overnight Windows update could have switched them around?

It’s best to move Manager data folder to Dropbox or similar. See https://www.manager.io/guides/10348

Thanks Lubos - Manager data files are on drobox, however something happened to the syncing and I had to re-install dropbox to correct the problem, so the recent backups hadn’t been synced.
The puzzle is that only part of the bank data is missing - 2018/19 is still there, but the coding has gone, and all the 2017/18 bank data has vanished from the file. Data prior to that is still there and coded. The 2017/18 data was imported as a .csv, and had been coded.
It was fortunate that I hadn’t emptied the recycle bin for a while, as I had tidied up the backup folder and just left one backup of each business.
No other businesses have been affected.
Fortunately not a disaster, only a few journal entries lost.
Regards
Peter

After I updated my laptop to the latest windows 10 release of May 2019 I lost my data.

This means that frequent backup is needed. Luckily for me I had backup up to the last data entry.

Put reminders on your devices (phone and computers) to make back ups. Synce them to the web. Copy them to external drives etc. Back up is critical.

It sounds to me like Dropbox restored an older version of your Manager data file - possibly because a newer version of the file did not sync properly or was detected by Dropbox as malware or some Dropbox update caused a problem.

You should only use Dropbox to sync between multiple computers. Don’t use Dropbox as your sole means of backup. If something goes wrong on one machine, it is synced to the cloud and then synced to the second machine. Get a backup program and backup all your data - not just your accounting file.