Everything to be Date format

Hi! I really Need help with my problem, in some days ago everything in my workbook to be Date formatted. I tried to make clear by reformatting the data one by one. But, the problem is every time I make a new sheet or in some new cell outside I have formatted, is to be date format. so, How to fix this, so that when I make a new sheet the default format is not date but as such as normally is "general".

 

Note: The problem is only in this workbook, but there's no problem with others.

Thank you very much. :)