Because I've been trying since 11am to get this done, I tried all the things suggested and more, but I still only get to 2% on the reconfiguring game files. I have messed up though, I got to 50% this morning and my PC froze, had to power off. now it just goes to 2%. I have deleted ftemp and update files from wow folder, probably stupidly i bet and I also tried to boot from wow.exe which i now know it a bad idea.
Can anyone tell me if i should reinstall then? how long will it take and how big is the file and, will it include this patch?
I tried the repair tool, all i got was patch info, the progress bar was 0% for over an hour, not seeming to work.

I just can't see any other way, I've rebooted so many tims, my PC is down to the bear bones, no av, no nothing. Ive tried, everything so far.... about to give in...