You can restore deleted items from Outlook Web Access published by exchange 2007 server as follow:

1. Login to your client access server- the link should look something like this:
https://client access server/owa
2. Click the Options link (up right of the OWA page).
4. Select Deleted Items from the option list (left side of the OWA page).
5. Choose the items you want to recover, click the "Recover".