weren't
v.v. the short way to say 'were not'. You use it to talk about more than one person or thing in the past.
v. the contracted form of 'were not'. Functions as the past plural or second-person singular indicative of 'be' in the negative.
They weren't at home when I called.
The students weren't prepared for the surprise test, so the teacher decided to postpone it until Friday.
If the conditions weren't so hazardous, the rescue team would have reached the summit hours ago, but the visibility made any further progress impossible.
were + -n't
Used with 'you', 'we', 'they', and plural nouns. In formal writing, the full form 'were not' is often preferred.
They wasn't thereThey weren't thereLearners often use 'wasn't' for all subjects, but 'weren't' must be used with plural subjects and 'you'.