WaXeD

ok so you go to the C:\Users\Richie\World of Warcraft Trial
(just to clarify, you have world of warcraft trial folder in a richie folder in the users folder on your C:\ drive... correct?)

do you see a WoW.exe in there now?

also, you used the download trial method so you have an executable installation file on your computer, correct?

uninstall like directed before, ensure all leftover folder and contents are gone..

ok now go to your installation file, right click and run as administrator.. this might be able to fix your problems.