Is the My Cloud visible and accessible (able to open Shares/folders) using Windows File Explorer?
If not then several of the suggested thing to check in Windows discussed in the following thread may help. In particular Windows 10 Specific Method 1 through Windows 10 Specific Method 5.
Also if one previously configured iTunes on the computer to use the My Cloud as the main iTunes media library they may need to check and ensure iTunes is still pointing to the My Cloud for it’s main library location. The following link, despite being for Macintosh’s indicates the general steps within iTunes to change the library location to an NAS device like the My Cloud.
