WoW bugged.

So guys , here comes my problem. Last night when I entered wow it started lagg really hard. For example when I get group invitation , it lagged and I had to restart wow every time that happened. I tought that's from WoW , cuz everything else was OK on my computer and I decided to delete it and download it again. After I did it , I wanted to start the game but I got this error (see the screen) , I never had that problem before. If any1 knows how to fix it I will be very thankful.

Here is the screen: https://scontent-fra3-1.xx.fbcdn.net...05&oe=55DBDF50

It says: The version of this file is not the same as the version of your Windows. Check system information on your computer, to see if you need x86 (32-bit) or x64 (64-bit) version of the program and than contact with the software publisher.

To say again , I have never had this error till now, I am using this Windows since 2013.