If you use a PC, you can use software you already have on your computer to retrieve some of the content. Right-click on the corrupt file and choose ‘Open With’ and select the Notepad program that comes bundled with every copy of Windows. The resulting file will contain a lot of coding but within that coding you will see the content. This is perhaps a only really viable with text-only PDFs as when you are dealing with images and forms, Notepad will be swamped with coding and finding the text can be the proverbial needle in the haystack.