Can't save PDF file in readable format

Hi,

I cannot download a file and save it in a readble format. It downloads from email and, when I open it, it is fine. If I then open it in the download folder it is unreadable. It is a PDF file from an original excel.

I could do it a couple of days ago but I have changed something (by trying to edit the file that I successfully downloaded and saved last week).

I can still download and save other files.

Can anyone help me work out what has changed and how to fix it?

Many thanks,