Thanks for looking for an advice in the Community! Sorry for the belated reply and hope you don't mind me answering in English 🙂
What you could try is performing a clean reinstall. Make sure to follow each step of the process. Then log out and back in.
Note: After reinstalling, you must download all your music for offline listening again.
If this doesn't fix it and the songs appears grayed out, it is likely due to unavailability in your country. Availability can change over time and between countries, depending on the permissions from rights holders. We do however add new music on Spotify every day. The missing conent might soon reappear!
Hope this helps 🙂
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