I've been having Minecraft ever since Late-Alpha and Early-Beta and I've never had problems logging in. But lately, whenever I try to log in the client I keep getting "Login Failed". I have a migrated account so when I put my username it says to use my email. When I go to my Mojang account I use the same email and password and yet I still log in. But when I log in the client everything goes wrong.
Also, are you able to login at minecraft.net?
I've deleted my .minecraft (saved my worlds) and re-downloaded Minecraft in the browser many times. I can even log in minecraft.net with no problem.