Looping the function if the input is not string

Question

I'm new to python (first of all) I have a homework to do a function about checking if an item exists in a dictionary or not.

inventory = {"apple" : 50, "orange" : 50, "pineapple" : 70, "strawberry" : 30}

def check_item():
    x = input("Enter the fruit's name: ")
    if not x.isalpha():
        print("Error! You need to type the name of the fruit")
    elif x in inventory:
        print("Fruit found:", x)
        print("Inventory available:", inventory[x],"KG")
    else:
        print("Fruit not found")
check_item()

I want the function to loop again only if the input written is not string. I've tried to type return Under print("Error! You need to type the name of the fruit") but didn't work. Help