Python-Code

# Imports
from string import ascii_lowercase
from random import randint

# Initiate pool of available chars
charpool = list(ascii_lowercase)

# Perform loop as long as charpool not empty
while len(charpool) > 0:

    # Get random number
    nextchar = randint(0, len(charpool)) - 1
    # Print Char
    print("Your Letter is: " + str(charpool.pop(nextchar)))
    
    if len(charpool) != 0:
     
        # Need more chars?
        answer = input("Do you need another char? (Y/n)")
    
        if answer != "" and answer != "y" and answer != "Y":
            break
    else:
        print("All letters have been used!")