https://forums.linuxmint.com/viewtopic.php?t=284037

Can you get them back? No.

But you can install the full version of xscreensaver and override cinnamon-screensaver. Please note that will also replace the Cinnamon lock-screen with the somewhat retro xscreensaver lock screen. I give no comment on whether the xscreensaver lock-screen is equally as secure.

Step 1 - Take a Timeshift snapshot just in case this goes horribly wrong and you need to revert

Step 2 - Disable cinnamon-screensaver

Run this command in a terminal. if you have multiple users you will need to do this for each user account.

gsettings set org.cinnamon.desktop.session idle-delay 0 && gsettings set org.cinnamon.desktop.screensaver idle-activation-enabled false && gsettings set org.cinnamon.desktop.screensaver lock-enabled false

Step 3 - Install xscreensaver

Run this command in a terminal.

apt install xscreensaver xscreensaver-data-extra xscreensaver-gl xscreensaver-gl-extra

Step 4- Link the cinnamon-screensaver-command to xscreensaver-command

Run this command in a terminal.

sudo ln -sf /usr/bin/xscreensaver-command /usr/bin/cinnamon-screensaver-command

Please note this link will be overwritten by any future updates to the cinnamon-screensaver package. Simply rerun this command after any update to cinnamon-screensaver,

Step 5 - Set xscreensaver to start at user logon

Open Startup Applications and add a custom startup entry with no delay to run the command xscreensaver if you have multiple users you will need to do this for each user account.



Step 6 - Reboot

Step 7 - Set up your xscreensaver preferences

In the menu xscreensaver properties can be found in the preferences category as a 2nd Screensaver entry with the description Change screensaver properties. Alternatively you can launch it from the terminal with the command xscreensaver-demo. Most of the settings are self-explanatory. Blank time is the idle time before the screensaver kicks in.



Step 8 - Test

If all has gone well your menu lock screen shortcut and Ctrl-Alt-L keyboard shortcut should lock the screen with the xscreensaver lock-screen. The screensaver should kick in after your specified idle time and if you have set it to lock after a time period in xscreensaver properties that should work too.

How to revert

Step 1 and 2 will need to be applied in each user account the changes were applied to originally.

Step 1 - Remove the startup application entry for xscreensaver

Step 2 - revert the dconf changes

gsettings reset org.cinnamon.desktop.session idle-delay && gsettings reset org.cinnamon.desktop.screensaver idle-activation-enabled && gsettings reset org.cinnamon.desktop.screensaver lock-enabled

Step 3 - Use Timeshift to revert back to a snapshot prior to xscreensaver install or carry on to Step 4

Step 4 - Reinstall cinnamon-screensaver to fix the link

apt install --reinstall cinnamon-screensaver

Step 5 - Remove xscreensaver

apt purge --autoremove xscreensaver xscreensaver-data xscreensaver-data-extra xscreensaver-gl xscreensaver-gl-extra

Edit to clarify that the gsettings commands are user account specific.