Repairing Data Error
As per Anet support desk;
If you are having problems running Guild Wars 2, the data archive may have become corrupted. Please follow these steps to verify and repair the archive:
Locate your Gw2.exe file.
Right-click on the file and select Create shortcut.
Rename this new shortcut to Guild Wars 2 Repair.
Right-click on Guild Wars 2 Repair and select Properties.
Locate the Target line and add -repair to the end.
Example: “C:\Games\Guild Wars 2\gw2.exe” -repair
Click OK.
Double-clicking Guild Wars 2 Repair will begin the repair process. The game will launch when it is complete.
Note: Keep in mind that the verification and repair process will run each time you double-click the Guild Wars 2 Repair shortcut. If you would like to play the game immediately without repairing the archive, double-click on Gw2.exe or another shortcut without the -repair command.
I did the same thing but all I did was run gw2.exe and it worked thanks for the help it fixed the error