Can you please check these sentences? I forgot to include them before. I really need to check them with you.

1) My family and I have been on holiday in (to?) Greece (he has come back from Greece). We stayed on (not in) Mikonos, a little island...
2) There wasn't (any necessary?) wind.
Unfortuanately I spent there only a week
I have just finished my dinner (but finished "having dinner")
3) I and my family went to Rome last month.
On Monday starts the school but I still haven't bought a pencil case.
4) I'm sorry we've never been in touch recently.
5) I've been on holiday (I was on holiday) and I came back last week.
There I met a girl called...., who is 15 years old just like us.
6) When I came back home I was very sad because I still had to do my homework and study.
What was your holiday like? How was your holiday?
7) I hope to receive an answer soon (your prompt reply, a quick reply from you'')
Keep me up to date with what happens to you.
8) I've had a busy month. I've been (or was) on holiday for one week. I went skiing in France with my family. The place was wonderful. I arrived yestarday and I have done some homework but I haven't finished it yet.
9) I still have a lot of things to study because school starts tomorrow.

There are VERY few errors either in this post or your last one. Choose the ones you have real concerns about -- max of 5 between the two posts.

Sure! Here are the corrections and suggestions for the sentences you provided:

1) My family and I have just come back from our holiday in Greece. We stayed on the island of Mykonos, a beautiful little island...

2) There wasn't any wind.

3) Last month, my family and I went to Rome. The school starts on Monday, but I still haven't bought a pencil case.

4) I'm sorry we haven't been in touch recently.

5) I was on holiday until last week when I came back. There, I met a girl called... who is 15 years old, just like us.

6) When I came back home, I was very sad because I still had to do my homework and study. (Both "homework" and "study" can be used without "my" in front of them.)

7) I hope to receive a prompt reply from you. Please keep me updated on what is happening with you.

8) I've had a busy month. I went on holiday for one week and went skiing in France with my family. The place was wonderful. I arrived yesterday and have done some homework, but I haven't finished it yet.

9) I still have a lot of things to study because school starts tomorrow.

I made corrections to grammar, word choices, and phrasing in the sentences. Remember to be consistent with tenses and use the correct prepositions.