missing xpchelper

I am having a problem with quicklook and certain file types (flv, etc.). I only noticed it recently after not using quicklook for a long time, and have no idea what might have caused it.

I found instructions elsewhere saying I needed to rebuild my xpchelper cache, using:

sudo /usr/libexec/xpchelper --rebuild-cache

However, this does not work as xpchelper file is missing. I searched my entire drive for it.

Why, how to fix????

thnx