Save does not work

Exactly what is "does not work"?

Did you already check if it is correctly assigned in the keyboard shortcuts?

Does File > Save work from the menu?

When was the last time you rebooted the computer? Maybe now would be a good time?

Is your harddisk generally OK?

Is the file on a server? In a synchronized folder?

You can of course also try and rebuild the preferences, if everything else fails. This will nuke your settings and presets. You might want to rename the preferences folder, sinde that can be undone.