It's perfectly fine to start sentences with 'and', 'but', or 'or'. But, you need to make sure to capitalize them, as with every beginning of a sentence.

i never claimed to have written a sentence

Claim or no claim, you did write a sentence.

nope

Yup

nope

Yup

nope

i was told in school not to start with but and or or?!

mom!

i was told in school not to start with but and or or?!

And I was taught in school that Columbus set out to prove that the world was round. Unfortunately, we're taught a lot of crap.

well....

Ok, this has left the serious side of things again.

Serious people can't smile. He has a small smile.

Whatever, that's clearly a micro-expression combining contempt and slight anger(beginning of the movement needed to bare teeth), in response to people who don't take the image seriously enough.

[pretends to sound smart] , [no one listens]

I'm sorry I misunderstood the picture. I now see how much expression is in that face.

you better

Firstly, 'you' should be replaced by "You", and there needs to be a full stop at the end of the sentence.

Secondly, thank you for calling me better.