Hello Violetta, 

First of all Kurt has done a pretty good job of the corrections but there are a couple of bits I would like to add.

A melomaniac is someone who is passionate about music. It is the first time in my life (as a native speaker) that I have ever heard the word and I think it would be too formal in a letter to a friend. I would say ...... all of my family really love music ....

We would also use the expression over and over again to describe a repeated action .. my brother likes to liste to the same song over and over again ........

Best wishes

Bob

Letter

Hello! I need someone to check out my letter for a exam. There is a task: "You've got a letter from your English pen-friend. In his/her letter he/she describes his/her impressions of visiting festival of modern pop-music. Write a letter to your pen-friend and say
what kind of music you like best
how your favorite kind of music makes you feel"

Dear friend,
Thank you for your letter. It was great to hear from you again after such a long time. I really should have written sooner but I have been busy with my exams.
It is nice to me to hear that you had fun at the pop music festival. I know that you wanted to visit it very much. I hope you met the group that you like and got an autograph.
In your last letter you wrote that you like only pop-music, and I have to say that I like all of genres. In my opinion every kind of music is great, and every of them deserve recognition. By the way, all members of my family are melomans [what is a meloman?] too. For example, my brother likes to listen one song again and again until he gets bored. Usually my preferences changes depending on my mood, and it is hard to say what music (fun or sad, fast or slow) I like more.
Looking forward to hearing from you!

Violetta.

===

Hi Violetta. I've marked grammar, punctuation and spelling corrections in yellow, phrasing adjustments in blue and vocabulary notes in magenta.

I hope that helps.

Letter

Love,

Violetta

Letter

Love,

Violetta