It’s very hard to say what is going on.
The file is likely empty because it was deleted at some point and now you clicked on a link and recreated it empty.
Is it possible that you renamed or moved this file?
Aside if this a problem with Obsidian or not (it would be great to have reproduceble steps), you really need to have some form of backup in place for your important sfuff.
You can try recurva as suggested.
You can also look at .trash/ in your vault and the system recycle bin.