WotLK Patch needed?

[Nekookie]

So I used to play a lot during summer but since I started school 3 months ago I stopped for a while. I wanted to start playing again so when I opened the game today, after logging in it said it needed to update, so I waited for a few seconds, after which it said I needed a patch and told me to restart the game. Since I haven't been here for about 2 and a half months I'm confused, should I download the game all over for it to work or is there a patch somewhere that I need to download?
I should also mention that I logged in with my email since logging in with my username did nothing.

[Zelta]

Make sure you are logging in with your username, not email.