[2020] Save files disappeared

Local save files are in Documents/paradox/ck3/save games/ folder - do you see them there?

If this is the Steam edition, cloud saves can be seen here:

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Do they end in .ck3 or anything else such as .ck3.tmp ? You may have to go into their properties to check for sure.

If anything other than .ck3 you could rename them to end in .ck3 and they may well be able to load then.  

Just check that as it's pretty much your only hope for recovering them. In Windows Explorer click on View up the top and tick File Extensions.

If no good, they are corrupted I'm afraid. You could look in Documents/paradox/ck3/ for last_save.ck3 - conceivably that one is okay!