Help:Reverting Content to Previous Version
You can do revert to a previous version of an article in a couple of ways. But first navigate to the article that needs to be reverted. Then go to the History page.
1) You can go down the page to the last good version and click on Prev. When the two versions come up, click on (Edit) on the column on the left. This will open up an Edit Window which you can then Save.
2) Or you can click on Rollback, it should take the page back to where it was when the last person before you edited it.