Notes auto-save as you type, so a crash shouldn't cause you to lose more than a few words.
Restart in Troubleshooting Mode (Help → "Restart in Troubleshooting Mode…”), which temporarily disables all plugins. If that fixes it, you'll need to identify the plugin that's causing it and then report the problem to the plugin's developer.
If not, click on the note in the web library and let us know the zotero.org URL.
You should also make a backup of the zotero.sqlite.bak files in your Zotero data directory. Depending on when you edited the note, you might be able to restore from one of those. You can see the timestamps of the backups files to see when they're from and whether they might contain the note contents.
That note is indeed empty, but just to be clear, that note was created only 15 minutes before its last edit, a few hours ago. Is that the note you're looking for?
OK, that note was created in September, and the last edit was on January 6.
Did you check both automatic backups? Is there one from before the 6th?
I'm afraid I can't tell you why the note would've become empty — that's not a normal thing that ever happen during a crash. If you were using some plugins, it's possible some plugin affected this.
Upgrade Storage
Restart in Troubleshooting Mode (Help → "Restart in Troubleshooting Mode…”), which temporarily disables all plugins. If that fixes it, you'll need to identify the plugin that's causing it and then report the problem to the plugin's developer.
If not, click on the note in the web library and let us know the zotero.org URL.
https://s3.amazonaws.com/zotero.org/images/forums/u12298626/49gnub6vlqcjggganqjv.png
Did you check both automatic backups? Is there one from before the 6th?
I'm afraid I can't tell you why the note would've become empty — that's not a normal thing that ever happen during a crash. If you were using some plugins, it's possible some plugin affected this.
https://s3.amazonaws.com/zotero.org/images/forums/u12298626/qo37i0xrsw971ahwxmy4.png