I think you are 100% looking for a magical capsule :D which you can get from harry potter movie :D
otherwise in the real world EXPOSURE  is the solution

talking to english speakers daily. it's the only way.

Hi Seif, that's a very fair question.  One advantage of learning English is that there is a lot of helpful information and materials online.  For example, look up videos with the keywords "<em>pronunciation th english</em>" and you'll find instructional videos.

It's a great resource we have today! :)

I think Bruce's suggestions are exceptionally useful, not only for pronunciation and rhythm, but also the culture of English. Sure, they are "children's" songs, but all native English speakers grow up singing them! :)

 Here are some examples to get you started:

These will help your speaking practice.

"Handy Pandy"

Handy Pandy, Jack-a-dandy,
Loves plum cake and sugar candy.
He bought some at a grocer's shop,
And out he came, hop, hop, hop!

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"Hey! diddle, diddle..."
by Mother Goose

Hey! diddle, diddle,
The cat and the fiddle,
The cow jumped over the moon;
The little dog laughed
To see such sport,
And the dish ran away with the spoon.

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"Jack be Nimble"

Jack be nimble
Jack be quick
Jack jump over
The candlestick.

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"Patty Cake"

Patty cake, patty cake baker’s man
Bake me a cake as fast as you can
Roll the dough and mark it with "B"
And throw it in the oven for baby and me

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"Humpty Dumpty"

Humpty Dumpty sat on a wall.

Humpty Dumpty had a great fall.

All the King's horses and all the King's Men,

Couldn't put Humpty together again.

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The Ten O'Clock Scholar

A diller, a dollar, a ten o'clock scholar!
What makes you come so soon?
You used to come at ten o'clock,
But now you come at noon.

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http://www.apples4theteacher.com/mother-goose-nursery-rhymes/handy-pandy.html

   You might use the Nursery Rhymes and children's books

like the American Children   are given to practice English.

.

  If you can find them on YouTube,  you can listen and repeat.

   The printed lyrics to Nursery Rhymes can be found on websites

like this one:

http://www.apples4theteacher.com/mother-goose-nursery-rhymes/handy-pandy.html

  Here is a good list to start with:

"Twinkle Twinkle Little Star"
"Trot, Trot, Trot" (...go and never stop)
"Ten Little Indians"
"This Old Man"
"Sx Little Duckies"
"I'm A Little Teapot"
"Old MacDonald Had A Farm"
"There Were Ten In A Bed"
"The Ants Go Marching"
"Jack and Jill"
"There Was An Old Lady Who Swallowed A Fly"
"The House That Jack Built"
"How Doth The Little Crocodile"

Then advance to short Stories like "Green Eggs and Ham" by Dr. Seuss
"The Cat In The Hat" by Dr. Seuss
"The Cat in the Hat Comes Back" by Dr. Seuss
"There's No Place Like Space" by Dr. Seuss
"Oh The Places You'll Go" by Dr. Seuss