Spirit theme has got inactive automatically?

Spirit theme was made active all these time and we were working on it. when I simply opened upfront today morning, upfront did not load spirit theme at all. so i just returned back to dashboard. Then i noticed that the output page of spirit theme what was there yesterday also got changed immediately to a test page which was there under PAGES.
Not sure how this actually happend. Pls try to findout the reason and let me know.