Weird: Suddenly my character styles panel does not allow any style to be edited. What could have happened?
Clarification: I click on Character Style 1 (eg) and nothing happens. Iclick again and I receive an error sound.
What operating system?
What version of InDesign?
All files or just one particular file?
One step that is common fix is to reset your preferences
If just one file try File>Export and choose IDML
Open that (opens in InDesign)
The Shift+Ctrl+Alt did nothing (although Windows 10 Pro did ask for permission to change this PC when I launched ID.)
I am using a current uptodate .subscription of the MENA Ver.
This is happening to all files in all languages.
I don't understand what you mean.
When launching indesign - hold down the key commands.
You'll be prompted to reset your preferences.
I think the OP is using Middle East North Africa verion of ID.
If trashing prefs fails, I think the next step would be to see if the problem persists under a new user account on the same machine. If it does perhaps an uninstall and running the CC Cleaner tool is in order.
If it works under a new user, looking for a software conflict (browser extension, background task, etc.) would be the next step.
The term OP is unknown to me.
How do I trash preferences?
The advice given to me so far has been to hold CTR-ALT-DEL key when entering ID. This is supposed to popup a preference choice box. No such thing is happening when I do it (repeated times.)
I would hesitate to use the CC Cleaner app as I dont think I have the expertise to venture into that realm.
In a similar vein, I do not even know what you mean by "...looking for a software conflict (browser extension, background task, etc...."
OP is forum shorthand for "Original Poster," in this case you. Resetting, replacing, and "trashing" the preferences are all the tems for the same thing, which you have done.
Did you try creating a new user account on the computer to see if InDesign works properly when logged into that account? If if does, the likely problem is some sort of conflict with other software that runs in the background when logged into your normal user account. Common culprits are things like password managers and other browser add-ons. One way to test that is to do a "Clean Boot" which starts your computer without non-essential programs running (Google clean boot and your OS if you are not familiar with how to do that).
The CC Cleaner tool is a last resort kind of measure and it does have some risks, but I think it's more likely not to do any damage. It is time consuming, however, as you need to reinstall all of your Adobe software after running the tool. See Use the Creative Cloud Cleaner tool to solve installation problems