emacs fonts (my stupid mistake, perhaps)

[Globe Trotter]

Hi, 

I like using the 10x20 font for emacs, and do so using 

emacs -fn10x20

However, when I do this on my F11 installation, I get: "No fonts match '10x20' ". 

I think I must have done something stupid to get here, but I don't recall doing anything strange and out of the ordinary over the past 2 days. In any case, how does one get my preferred font back?

Many thanks and best wishes,
T