minecraft bugs

Put the summary of the bug you're having here

What I expected to happen was...:
I could open minecraft and play shaders mod happily

What actually happened was...:
It said's "can't connect to minecraft.net"
and I can't play offline because it said i didn't downloaded it but I already bought the full version
Steps to Reproduce:
1.open minecraft
2.type in username and password
3.bug happened