How do you convert a .bak extension file into a DIALux file?

Question

Today I was working on a large DIALux file (a .dlx file). It suddenly went missing. I think I saved over it with another blank file. I still have a saved version as a .bak file, but do not know how to convert this to a .dlx file. Can you help?

Answer 1

You have to rename the file extension from .bak to .dlx. After that, DIALux will recognize and open this file. If your file extension is not visible, you need to go at Start > Control Panel > Appearance and Personalization > Folder Options > View tab. Clear the Hide extensions for known file types, check box and then click OK. Go to your file, right click on it and select Rename. Delete .bak and type .dlx instead.

Answer 2

This option does not work as when you go to the file properties it still shows
yourfilename.dlx.bak and because it is a .bak type dialux can't open it.
So still how do I change that or recover the magically corrupted file?

Thank you very much as over 30 hours of work had been lost!