What is the difference in use between yüzden and yüzünden? Are they interchangeable?

If anybody can enlighten me, I´d appreciate it.

Thank you.

I´m not sure about grammatical rules, but I tried to help you. 

1) "bu yüzden" or "o yüzden" are used for

because of this or that.

2) "senin yüzünden" is used for

because of you.

3) "sizin yüzünüzden" is used for

because of you.

4) "Onun yüzünden"

because of him/her.

5) "Onlarýn yüzünden"

because of them.  

You´re welcome.

* If you need more help or explanation, please inform us. But if you ask questions with some example sentences, it will be more benefical for you.

Thank you seyit, this is very helpful. I have another question though. If you use a noun instead of a personal pronoun do you add -(i)n to it?

For example, is it correct to say:

a) Havanýn yüzünde uçak seferleri iptal oldu.

or

b) Hava yüzünde uçak seferleri iptal oldu.

Thank you.

Kötü hava (koþullarý) yüzünden uçak seferleri iptal oldu. 

Because of bad weather (conditions) flights were cancelled. ? Is it correct?

Thank you Seyit.

Your translation is correct, although I think it would sound nicer this way:

"The flights were (or have been) cancelled because of bad weather conditions."

Let me also throw back a question at you. Is "koþul" synonymous with "durum"?

Would it be correct to say: "Kötü hava durumu yüzünden uçak seferleri iptal oldu."?

Thank you.