Question

Can you start a sentence with but or and

Answer 1

it is better to put it in a sentence then to start the sentence with it. For example :

What loos and sounds better?

I wanted ice cream, but i'm lactose intolerant.

or

I wanted ice cream. But i'm lactose intolerant.

Answer 2

Usually you can not, but you can combine them using a comma to make one sentence.