Is that what you did…

1. Open an email
2. open the attachment in the email
3. start working on the attachment in perhaps Word or Excel
4. then closed it and move on to another email
5. then a day later you go back to the message and wonder where the attachment is with the edits?

Try this to get to that file: https://www.howto-outlook.com/faq/securetemp.htm

here are some directions:

1. Click Start, then type Run and enter Regedit
2. When the registry appears, follow the instructions in the article based on your version of Outlook
3. Once you find the path, copy that into Windows Explorer
4. The attachments in your email should appear