I haven't took your class for a long time.
I didn't take your class for a long time.
Which one is more appropriate?
I haven't took your class for a long time.
I didn't take your class for a long time.
Which one is more appropriate?
I will try to answer – I am a newcomer to this site, but I have more than 20 years' experience as a book editor.
Your first sentence, I think, expresses your intended meaning more clearly than the second, but you need to replace took with taken, which is the past participle of the verb to take. I haven't taken your class for a long time. So it's something you have done, but it's in the past.
The second sentence is grammatically correct, but its meaning is different. It almost needs an explanation. For example, I didn't take your class for a long time because it was held at a time that did not suit me.