I'd suggest to use while True loops, so you can put the input code once, then with the correct condition and break you're ok

while True:
    problem = input("Do you have a problem in life? ").lower().strip()

    if problem not in ("yes", "no"):
        print("Please enter YES or NO")
        continue

    if problem == "no":
        break

    while True:
        something = input("Do you have something to do about it? ").lower().strip()
        if something not in ("yes", "no"):
            print("Please enter YES or NO")
            continue
        break
    break

print("Then why worry?")

Using walrus operator (py>=3.8) that could be done easier

while (problem := input("Do you have a problem in life? ").lower().strip()) not in ("yes", "no"):
    pass
if problem == "yes":
    while (something := input("Do you have something to do about it? ").lower().strip()) not in ("yes", "no"):
        pass

print("Then why worry?")

Try this:

Copy
inputnum = raw_input ("Please enter a number.")
num = int(inputnum)

if num >= 0:
    print("The number you entered is " + str(num))

you don't need the else part just because the code is not inside a method/function.

I agree with the other comment - as a beginner you may want to change your IDE to one that will be of more help to you (especially with such easy to fix syntax related errors)

(I was pretty sure, that print should be on a new line and intended, but... I was wrong.)