how can I restore default fonts in Ubuntu 11.10?

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http://askubuntu.com – I have accidentally deleted some of the fonts from /usr/share/fonts folder. They must have been crucial since now I have various display problems ( underscore and font size display ). I have already tried resetting gnome and system fonts settings but it does not solve the problem. It seems that I need the missing fonts files but I don't remember the names. Do you know where I can find a list of preinstalled fonts of Ubuntu 11.10, so that I can locate and restore the missing files ? (HowTos)