I can fix it using beach-dix’s method, but I do the followings to save my settings:
Close NP++
Go to NP++ directory
Rename config.xml to config_backup.xml
Copy config.model.xml to config.xml
Start NP++
Check if it’s fixed.
Close NP++
Delete config.xml
Rename config_backup.xml to config.xml
Start NP++
So the config file isn’t changed in the end, but when I started NP++ with a new config.xml something got reset, then I could copy back my configs.