How can I retrieve Archive items that I accidentally deleted?

When you delete a file it goes to the Trash. To recover the file before emptying the Trash simply right click the file and select the Put Back feature. If you have already emptied the Trash then the file is gone forever unless you backed up the computer. If you backed up the computer using Time Machine then simply restore the file from your Time Machine backup. If you use another form of backup, please speak to the developers to learn how to restore files and folders from their backup app.