Replacing number in a string by 0(zero)

Question

This is my code. it does not work. My goal is to replace numbers in the string by 0

str=input()
for i in range(len(str)):
if ord(str[i])>=48 and ord(str[i])<=57:
str.replace(str[i],"0")
print(str)

//Help me...

Answer 1

str=input()
for i in range(len(str)):
if ord(str[i])>=48 and ord(str[i])<=57:
str=str.replace(str[i],"0")
print(str)