Excel Date Format Cleanup

I have an Excel workbook where every date column is a mess of mixed-up formats. Nothing is missing; the problem is strictly that the existing entries are stored in multiple, incorrect styles. I need each of those values converted and locked into the DD/MM/YYYY format across the entire file... (Budget: ₹100 - ₹400 INR, Jobs: Excel, Excel Macros, Excel VBA, Visual Basic)