My disk is almost full but hard drive isn't

mountaincat99 wrote:

I don't understand why the HD Info would say Capacity 500 GB, Available 338 GB, and Used 496.29 GB.

When Apple says "Available", it means that is storage that "could become" free if you really needed. But, of course, whether or not you need it is Apple's decision. 😄 To calculate your actual free space, take your capacity and subtract the used amount. 500 - 496.29 = 3.71 GB of actual free space.

In theory, after a while, your machine may turn some of that "available" space into "free" space that you can use. Hopefully that will happen before you experience a catastrophic failure. You are only 3.71 GB away from that. Modern Apple operating systems consider unused storage to be wasted storage.

Luckily, you downloaded EtreCheckPro. Go to the Tools menu and use the "Storage" tool. That will show you which folders are taking up all of your storage. It will only allow easy access to those folders where you can safely delete files. It will also give you an easy method to delete local snapshots. Deleting those local snapshots should recovery a significant amount of storage in your case.

PS: I reviewed your EtreCheck report. Unfortunately, you are well into that catastrophic failure stage. I think your local snapshots are growing out of control because you aren't doing regular backups. You could have an unrecoverable failure at any time. You should connect your backup drive and make a backup. Do this now.

Then, try to delete local snapshots and review other storage to free up space.

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You have some adware installed. Use Etrecheck to remove them or download and run the free version of Malwarebytes. It was developed by a long time contributor to these forums and a highly respected member of the computer security community. 

You also have some unnecessary software on your Mac that probably is contributing to the degradation in performance: AVG. Uninstall it according to the developer's instructions: How to uninstall free AVG AntiVirus for Mac

There is no reason to ever run any "cleaning", "optimizing", "speed-up" or anti-virus apps on your Mac. This user tip describes what you need to know and do to protect your Mac: Effective defenses against malware and other threats - Apple Community   

Until you fix the local snapshots, you will probably continue to have problems with free space and not recovering storage after deleting files. You have local snapshots from February and 2019. That means that if you attempt to delete any file created before October, 2016, you will not recovery any space.

As I mentioned above, you may be able to use EtreCheckPro to delete those local snapshots.

What does the Info pane for your hard drive indicate for available space?

Boot into the Recovery volume (boot with the Command + R keys held down), select Disk Utility and run First Aid on your drive. Reboot normally and see if there's any change.

AND there are NO viruses for Macs, none!

Also download and run Etrecheck. Etrecheck is a diagnostic tool that was developed by one of the most respected users here in the ASC and recommended by Apple Support  to provide a snapshot of the system and help identify the more obvious culprits that can adversely affect a Mac's performance.

Copy the report

and use the Add Text button to include the report in your reply. How to use the Add Text Feature When Posting Large Amounts of Text, i.e. an Etrecheck Report

IMPORTANT:

Before running Etrecheck assign Full Disk Access to Etrecheck in the Etrecheck's Privacy preference pane so that it can get additional information from the Console and log files for the report:

Then we can examine the report and see if we can determine what might be causing the problem.

That shouldn't be related but there is definently a chance for anything. So for your hard drive you could either go to apple support in person (I recommend) or you could try to backup your files to a usb drive and buy another hard drive? (When you can't turn off your MacBook that may be a physical problem? If I were you I would go to your nearest apple store.