I.            Bunu çok nefisi görünüyor ama maalesef yemeyeceğim .

      II.            Geçen hafta regim basladi bu yüzden etli yemek ve hamur işi bana yasak.

   III.            Düzenli yazarim ama yazar olamam çünkü yetenekli değilim.  

   IV.            Pardon, bu rengi hiç yakişmiyorum. Masmavi bluzu bulur misiniz?

      V.            Yeğenim yuzünün müthiş benzerliğim.   

I´m not sure whether I should use gecen hafta or gecen haftayı?

Ive seen this

Fernandes geçen haftayı arattı

and

Messi Geçen Haftayı Unutmamış!

Do we add the ı suffix because gecen hafta has become a direct object of the verb?

sorry to be so persistent but would someone please correct my sentences if possible?

Thanks in advance =)

Absolutely ! 

Thank you Tunci you are very helpful =)

Are my other sentences  grammatically okay as well?

Thank you very much. Just a one question: Can you please explain why you put ´olarak´ as my intended sentence was :

I write frequently but I am not a writer because I am not talented (my intended sentence)

I knew when I was writing the last sentence that it seemed incorrect but I wanted to use ´benzerliğim´ in a sentence. My intended sentence was:

My niece resembles me alot.

Thank you again for being so helpful =))

1. Düzenli = regular 

   I just made it "regularly" , so I had to put "olarak" which functioned as "ly"

   I write regularly.........

However, if you wanted to say "frequently" we can say ;

  Sık sık yazarım.........

2. Benim [kız] yeğenim bana çok benzer. ---> My niece resembles me alot.

to resemble = benzemek 

bana = to me 

thanks!