I just had a similar problem but the client seems to pick up from where it left off. (Considering there's only 1 file left and you have a 15gb(?) .dat file in your Guild wars folder) you should be fine. --- 3DS - 0774-4234-8857 - Currently playing : Kid Icarus.
The reason some of the files don't seem to download is probably because developers made changes to those files the very moment you were downloading, so just restart the updater so it gets the latest update information. No download data will be lost and you won't be downloading from the beginning.