Starting from the version 42 Chrome blocks Silverlight by default.
To enable it:
- Type chrome://flags in the browser's address bar and hit Enter.
- Search for "Enable NPAPI" using Ctrl+F.
- Enable it with a click on the "Enable" link.
- Restart the browser.
Note: Chrome will not support Silverlight in the future (Sep 2015). For full info about issue see this article
Note2: Chrome may still decide to block the Silverlight plugin after you do the above steps and you will likely see this warning and suggested action(s) if this is the case - see this screenshot and check against your chrome warnings/errors