To resolve the issue of encountering a "this track is not available" message while trying to listen to downloaded music on eSound, follow these steps:

1. Check Your Internet Connection
Ensure your device is connected to the internet. Sometimes, downloaded tracks require a validation check through an internet connection.

2. Restart the eSound App
Close the eSound app completely and restart it. This can refresh the app’s performance and may resolve temporary glitches.

3. Verify Download Status
Go to your downloaded music library within eSound. Confirm that the tracks are fully downloaded and not just partially downloaded or displayed as "pending."

4. Update the App
Check if there is an update available for the eSound app. An outdated version may lead to functionality issues. You can update the app through the Google Play Store on your device.

5. Clear App Cache
The app's cache might contain corrupted data that can cause playback issues. To clear the cache, go to:
- Settings on your device
- Apps & Notifications
- Select eSound
- Choose Storage & Cache
- Tap on "Clear Cache"

6. Re-download the Tracks
If the problem persists, try deleting the specific tracks that are causing the issue and re-download them. This ensures that you have the latest version of these tracks.

7. Check Membership Status
Ensure that your eSound membership is active. If you are using a free version, some tracks may be unavailable due to licensing restrictions.

8. Contact Support
If after trying the steps above the issue remains, contacting eSound support can help. Provide them with detailed information about the problem you are facing.

These steps should help you resolve the playback issue for downloaded music on eSound. If the situation doesn't improve, further investigation into account settings or regional restrictions may be necessary - learn more - learn more - learn more.