My Cloud fell down and the Ethernet socket got broken, Went to many stores but non was able to fix it. Where can I fix it or where can I buy motherboard for my cloud?
Have you contacted WD Support directly to arrange for an RMA for WD to fix/replace the My Cloud?
http://support.wdc.com/contact.aspx?lang=en
Other then that about all you can do, if the network port broke clean off and cannot be resoldered back on, is try to find a used My Cloud enclosure or backplane on eBay or the like and swap the hard drive from your current My Cloud to the used My Cloud that has a functioning network port. Soldering in a new network port would be difficult if one cannot find the exact same networking port pinout used on the My Cloud.