A group of words that cannot stand alone as a sentence
You should not capitalize a sentence fragment following a colon.
Combine it with another sentence.
It is true
My best regards,
Do you work? is a complete sentence; it is not a sentence fragment.
fragment
"She wave." is fragment but "She waves" is a sentence.
Fragment.
sentence fragment
It is a sentence fragment
"After the storm," is not a complete sentence so it is a fragment.
Make each fragment into a complete sentence.