Data loss on MacBook

The most common reason Users report losing "all the files in my Account" on their computer is that they somehow managed to log in to a different Account than the one they expected.

MacOS is inherently a Multiple-user system, and nothing you do can change that. Users files are strongly protected from each other, and are all stored in sub-directories off the

/Users

... directory.

Excellent!

One problem we looked for today, but (luckily) did not find, was drive failure. Problems you reported might have indicated that your drive had failed, deleting all your files. This would mean you would lose everything. "Any drive can fail at any time."

¿Do you have a Trusted backup?

Time machine is built into MacOS. If you are using another backup method that you prefer, that is great. If not, you need to take steps to acquire an external drive as soon as possible. If you buy one, a drive 2 to 3 times or larger that your boot drive is preferable for long term trouble-free operation. Do not pay extra for a drive that is fast. (You can get by for a while with a "found" smaller drive if necessary, but it will eventually become annoying).

Attach your external drive and use

System preferences > Time Machine ...

... to turn on Time Machine. It may ask to initialize the new drive, and that is as expected.

Time Machine will then spend all afternoon making your first full backup. You can continue to do your regular work while it does this. The first Full Backup is by far the biggest backup. After that, it will work quietly and automatically in the background, without interrupting your regular work, and only save the incremental changes.

Executive Summary:

Time machine's "claim to fame" is that it is the backup that gets done, because it does not ruin performance of the rest of the computer while doing its backup operations. When you need it, it is much more likely to be there.