Regarding the use of the verb "demek"
This verb has baffled me for quite a bit, I know it's mainly used as "to tell" but can also be used in "ne demek?" as in "what does it mean?" So my question is: how would I use this verb to make a sentence like " I didn't mean that"; would it be "Böyle demedim"? also what other uses/meanings does this verb have?
thanks in advance
"Demek" means "to say" and "to mean" in the sense as you mentioned (eg. what does it mean?)
In order to say "I didn't mean that"; you can say "Öyle demek/söylemek istemedim" (I didn't want to say so) or "Onu kastetmedim" (I didn't mean it) -with Arabic loan.
So if I for example hit my friend in the face "accidentally" I would tell him "Pardon, Kastetmedim" right?
Oh that's actually different. What I mentioned was only when you said something wrong or the person got you wrong. In the cases we do something accidentally, we usually say "Yanlışlıkla oldu" which translates roughly to "it happened by mistake".