Excel prints blank

I receive Ecxel sheets from my partner and when I go to print, they are blank.

I've discovered that when I change the font globally to Geneva, the sheets print fine.

As they arrive, the sheets appear to contain the font Arial.
My Mac has this font but will not print it.

If the font is corrupt, how do I re-install it?

Thanks in advance for any suggestions?

As far as I can tell, the Arial font family is installed as part of the normal fonts included with OS X. Also, if you have MS Office installed the Arial fonts should be included. Open your Font Book application and check. It sounds like he may be using a different Arial font which is why it won't display.