I am afraid this can‘t be fixed except deciding which device has the most current/important database, uploading this one to AnkiWeb and use it to overwrite the data on other devices. If you have created/imported new content on any of these devices, you can export these notes and import them later after you have downloaded and overwritten the local database.
.
I think this excellent advice should be appended to the already very lengthy (and very scary) message that usually greets sync problems - and which is quoted in the OP.
You do not need to use sqlite3.exe. That is mentioned in a section of the manual describing how to recover from corruption, but it doesn’t sound like you have corruption here, and it sounds more like you accidentally overwrote recent changes with an older version of your collection.
Your AnkiWeb collection has a deck that mentions muscles, and you appear to have cards in it both from 3 weeks ago and yesterday. Is it possible you have found or were able to restore the cards you were missing?
.
So you’re using Anki on three different devices.
That’s a very productive way to use Anki. But you need to be alert for sync issues.
I use Anki on Windows and iPhone. My memory is no longer trustworthy. So I have a card in each Anki deck, similar to the following:
Front: What do I need to do at the end of each Anki session?
Back: Press “Sync”. Close Anki.
I Pass or Fail that card to ensure that I see it as frequently as I need to see it. That’s once per session.
Refer to the following post to use the “Everything” tool from Voidtools. It will search your complete hard drive in a few seconds. If you have any external drives mounted, it will search those as well: