If you can’t access Preferences, then you need to do a full reset of Cookie.
Quit Cookie first.
You can restore your settings,
by first making a copy of all the files in this folder:
Then delete this folder:
On macOS Catalina and earlier, the folder path is:
Quickly skip through the setup.
And replace the files you copied earlier.
Then you should be able to restart Cookie with all your browser settings and favorites.
You still need to go into Preferences and update any settings you had customised (start at login, hide dock icon etc…)