default settings

We restore at default settings “Full recovery” also cleared the contents of the disks (videos, music …) !?
I can no longer install apps, always comes the message “The app could not be installed” then wanted to try the solution.
My Cloud EX4100 with 4 * 6TB red.

You should do a power cycle and restart My Cloud EX4100, then try to install apps from the dashboard of My Cloud device. During power cycle of device, it will initialize the network path and helps to create new links with the My Cloud services.