I created one component from a/c username : testcook but it is not working in Sandbox when I access newly created component URL it displays blank page.

Hi,

Have you created a layout for the table/view (form and/or a grid) and dragged fields to it?

If so, try closing the tabs in the builder, rebuild the files and click the sandbox link again.

Any errors on page?

An admin side page or frontend?

Gez