My code doesn't work, can someone help me?

[jefsummers]

You are using num for the input, then expect that num will end up being the list that you can cycle over, and you also never append the integer to the list.
Minor changes, try:

largest = None
smallest = None
num = []
while True:
    num_input = input("Enter a number: ")
    if num_input == "done" : 
        break
    try:
        num1 = int(num_input)
        num.append(num1)
    except ValueError:
        print('Invalid input')
        continue
for number1 in num:
    if largest is None:
        largest = number1
    elif largest > number1:
        largest = number1
print("Maximum is", largest)
for number2 in num:
    if smallest is None:
        smallest = number2
    elif smallest < number2:
        smallest = number2
print("Minimum is", smallest)

Output:
Enter a number: 2
Enter a number: 8
Enter a number: 9
Enter a number: python
Invalid input
Enter a number: 4
Enter a number: 10
Enter a number: done
Maximum is 2
Minimum is 10