Not able to change date format into proper excel date format

Thanks to all beforehand. I am in need of excel formula or VBA Code to change date format from 05-30-2010 into 30-05-2010. Actually every month I received excel dump from different companies in which I received date format as given above as premium due date, I used different different excel formulas but not able to change its format into proper excel format. Kindly help me resolving this problem.

I used to use text to column then adding them using this formula =date(year(a1),month(a2),day(a3)). But rather I want formula or code for this solutions.

Excel sameple sheet is attached for reference.


Regards,
Pramod Kumar