I can no longer save jpegs and none of my icons are visible - I want the previous version back!

Here is some troubleshooting advice:

https://helpx.adobe.com/photoshop/kb/basic-trouble-shooting-steps.html

Perhaps try resetting Photoshop preferences?

(read this entire post before acting please)

Resetting restores Photoshop's internal preferences, which are saved when Photoshop closes.

If they become corrupt then various issues can occur.

Here’s some info on how to do that:

https://helpx.adobe.com/photoshop/using/preferences.html

Manually removing preferences files is the most complete method for restoring Photoshop to its default state: 

https://helpx.adobe.com/photoshop/using/preferences.html#Manually

The user Library folder is hidden by default on macOS.

To access files in the hidden user Library folder, see here for how to access hidden user library files.

https://helpx.adobe.com/x-productkb/global/access-hidden-user-library-files.html

Unexpected behavior may indicate damaged preferences. Restoring preferences to their default settings is a good idea when trying to troubleshoot unexpected behaviors in Photoshop. check out the video

https://helpx.adobe.com/photoshop/using/preferences.html#reset_preferences

Learn how to access and modify Photoshop preferences and customize per your frequent workflows

https://helpx.adobe.com/photoshop/using/preferences.html

And here’s an earlier forum discussion as an aid to understanding

https://community.adobe.com/t5/photoshop-ecosystem-discussions/quick-tips-how-to-reset-photoshop-preferences/td-p/12502668

You may want to backup your settings and custom presets, brushes & actions before restoring Photoshop's preferences.

Here is general info about that:  https://helpx.adobe.com/photoshop/using/preferences.html#BackupPhotoshoppreferences

I hope this helps

neil barstow, colourmanagement net :: adobe forum volunteer:: co-author: 'getting colour right'

google me "neil barstow colourmanagement" for lots of free articles on colour management

Are you using "save as" or exporting? I prefer Save As

I hope this helps
neil barstow, colourmanagement net :: adobe forum volunteer:: co-author: 'getting colour right'
google me "neil barstow colourmanagement" for lots of free articles on colour management

I've uninstalled the new versions and re-istalled the previous versions of the apps I use, but one thing hasn't changed back. When I've finished working on a raw file and click to save it as a jpeg in my chosen folder, it used to then automatically convert the file format to .jpg on the screen. However, now, it remains as a .cr2.  Is there a way to revert to the previous format as that is what is most useful to me?

If you want to return to the previous version, you can. Here's how:

• Install previous versions of your Creative Cloud apps

However, it sounds like your update wasn't set to Import previous settings and preferences. For future updates, you can select that option either when you manually update Creative Cloud apps or when you're in the Updates section of the Creative Cloud Desktop app, you can click Manage auto-updates, click Advanced options, and select it.