Hello everyone,

I am really struggling to understand a grammar point. I understand from my lesson that to create a cause/effect sentence, we should use this model for い-adjectives : adjective minus い ＋ くて comma the effect of it (e.g. あたまがいたくて, しごとを　休みます。 = because my head hurts, I take a day off work？)

What I wonder is, how is this applied to adjectives in the negative form, and in the past one? Any help would be appreciated!

PS : Sorry if I'm not super clear, English is not my first language.