Changing mass data's date format

[FrecklePaw]

I have two different spreadsheets with data entered by two different users, one has used the date format 00.00.00 and the other has used 00/00/0000. I've copied and pasted all of the info from one sheet into the other to combine them to make just one copy - they look the same except for the two date formats. As there's hundreds of them I obviously don't want to go through and amend every single entry - how can I do this automatically? Switching the Format Cells > Date doesn't work for this.
Thanks!

[HansV]

Try the following; I'd test it on a copy of the worksheet first.

Select a column with dates.
On the Data tab of the ribbon, click Text to Columns.
Click Next > twice, so that you are on Step 3 of the wizard.
Select Date, and select DMY from the dropdown next to it.
Click Finish.

If the result is not what you wanted/expected, you can undo the change by pressing Ctrl+Z.

[FrecklePaw]

Works like magic - thank you v much, would have never worked that out on my own! :)