If the files are JPG, highlight them in Windows Explorer, right-click and select "Properties". On the "Details" tab you can change the "Date taken" value in the "Origins" section.
You can adjust using the option 'Shift to new starting date and time'
Find the oldest file, calculate the right starting year, month and day, select all pictures with the same date shift, this will change the first file and the following accordingly. I have done this many times.
thanks, worked perfectly .