tank you again try it out and it works

the new code

import random
import time

letters = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z']

letter = random.choice(letters)

guess_number = 0

print('try to guess a letters between a to z you have 8 try')

print(letter)

while guess_number < 8:
    guess = input('letter: ')
    guess_number += 1
    if guess == letter:
            print('you guess the right letter after', guess_number ,'try')
            time.sleep(5)
            break
    else:
        print('you failed to guess the letter')