A family of Microsoft relational database management systems designed for ease of use.
Unfortunately, there are multiple possible explanations for data being unavailable to you when you look for it.
Some of those possible reasons include
- Accidental deletion by you or someone else who uses the database.
- Perhaps someone thought they were making a backup and archiving data or something like that.
- Perhaps someone deleted an accdb thinking it was older and not the current one.
- Restoration of an old, old backup without those records over the top of the newer accdb.
- Corruption in the accdb.
- Accidentally opening an old backup copy of the accdb instead of the one you thought you were opening.
It's highly unlikely that the records simply disappeared without some intervention by a user, or a mishap on your part or the part of someone else who uses the database.
I would start by doing a due diligence search to verify that you are now looking at the correct copy of the accdb. Make sure you or someone else didn't move files around for you inappropriately.
Verify with other users -- if there are any -- that no one else did something wrong, i.e. that no one accidently deleted records.
Make sure the accdb is not corrupted, i.e. that you can open it and browse all of the records still in it and that forms and reports work properly.
If I had to guess, and it would be a guess, I'd suspect you are actually not looking at the most recently working accdb, but an older copy that somehow found it's way into your path.