I deleted a folder and its contents in OE6. Is there any way I can get it back?

Did you already Empty the Deleted Items folder? If not, simply drag the folder to where you want it, or right click on it, select move then follow prompts.

I checked the deleted Items folder straight away and the deleted folder wasn't there?

It should be - unless you have under Tools > Options > Maintenance menu Empty messages from the 'Deleted Items' folder on exit check box ticked.

Note if the folder is there, you may have to click the "+" next to Deleted Items to see it.

If you emptied the messages - either manually or by the menu option, I don't how to recover that - perhaps someone else reading.