Argh!! (Really need your help)

I have a g.mail account that I use basically for tumblr and youtube. I went to login this morning and boom..."Username and password incorrect"
So, I double checked that everything was spelt correctly and reentered the password and username.

Low and behold- it didn't work again.

So, I decided to reset my password and got all the emails to say that I had successfully changed my password. I then tried to log in with my new password and again, the same thing happened all over again.
I've reset the password several times and searched through various forums to see if I could find any answers.

Does anyone know how to fix this or is this happening to you? I'm getting really frustrated.