Standard English does not have two negatives in the same clause (double negatives). Words such asnever, nobody, no one, none, nothing, nowhere, etc. already have a negative meaning, so we don’t need another negative with the verb:
There wasno onein the office so I left a message.
Not:There wasn’t no one…
Nobodylikes to think they are worthless.
Not:Nobody doesn’t like to think…
If we usenotwith the verb, we use words such asever,anybody,anyone,anything,anywhere, instead ofnever,nobody,no one,nothing,nowhere:
Ihaven’tseen Kenanywheretoday. In fact Idon’tthinkanyone’sseen him for the last couple of days.
Not:I haven’t seen Ken nowhere… orI don’t think no one’s seen him…
You may hear some speakers using two negatives in the same clause, but many people consider this to be incorrect.
Not … I don’t think
There are some cases where we can use reporting verbs such asimagine, supposeandthinkin end position, after the reported clause. In such cases, both clauses may have a negative verb:
He’snota teacher, Idon’tthink.(orIdon’t thinkhe’s a teacher.)
Not:I don’t think he’s not a teacher.
Iwon’tbe very late tonight, Ishouldn’timagine.(orIshouldn’t imagineI’ll be very late tonight.)
Not:I shouldn’t imagine I won’t be late.
Sometimes we usenotin front position where a following reduced clause (a clause with something omitted but which is understood) also has a negative form:
A:Have you seen Leila?
B:Nottoday, I haven’t. (I haven’t seen Leila/her.)
A:Is Tony working at the university?
B:Notnow, he isn’t.He used to.