Sidebar at bottom however I have completely replaced theme folder back to original code

A few things to note here:

1) You should never modify WordPress core files such as those found in “wp-includes” and “wp-admin” as it will only cause you trouble later down the road.

2) The sidebar issue you are reporting doesn’t appear to be happening in Chrome on the link you provided. Try clearing the cache on your browser or doing a “hard refresh” on it to see if the issue is still happening.

3) If you’ve added custom markup code in your “text” widget, try removing that code temporarily and refreshing the page. If the problem goes away, review the code for any markup errors before putting it back in.