One of our readers, Belgarionn, encountered an issue with the Guild Wars 2 patch process and discovered an elegant solution we thought we'd share in case others are having the same problem. Here's what Belgarionn had to say:
During a routine patch of GW2, my ISP hiccuped, and when it came back, the patch could no longer continue because it 'lost access to the GW2.dat file,' which is the only file in the folder other than the exe. There is no rebuild utility, even trying to repair from the DVD didn't work because it could not access the .dat file. The problem was that the file had become access-locked (a little padlock had appeared on the icon indicating that). I couldn't find a way to clear this through properties.
My solution was to copy the 14g .dat file. This cleared the lock on the copy. I then renamed the copy back to the original. I found this to be a Way better solution than uninstalling and reinstalling, which seems to be the only other option.
Our thanks to Belgarionn for sharing the solution at a time when the Guild Wars 2 official forums are temporarily closed.