Editing a PDF

I am trying to edit a PDF and when I go to replace a number is tells me There is no available glyphs for this symbol. The font used in this document is not installed on your system.  I can edit the text in the PDF just not the numbers.  Can you tell me how I can figure out what font is used and how to install.



you can see which font is being used by going to the edit tab.
Now select the edit or select tool and click somewhere in the text.
The font will be shown and changable from there.