The third person singular (he, she, and it) form of the verb to do in the present tense is does. Therefore, "sun doesn't shine," is the standard English form and the only form acceptable for English students.
Quite often, native writers will use non-standard dialect forms of English to add emphasis or "character" to their writing. This is especially true for invectives such as, "Put that where the sun don't shine." (Shove it up your a**)
Student or Learner