Question

last night,when I would play my guitar loudly,my neighbours complained (edit the sentence)

Answer 1

Last night I played my guitar loudly and the neighbors complained

Answer 2

Last night, I played my guitar loudly and my neighbours complained.

Explanation:

The question has future tense indication. But the subject had performed an action which resulted in conclusion too. So, it must be in past tense.

Would verb is not suitable here because it is not demanding an action but the subject has performed an action which has shown results. The "past form of the verb" can signify the action in the proper time based.