import os
import json
from os import error, listdir
from os.path import isfile, join

onlyfiles = [f for f in listdir("C:\\Users\\EGEMEN\\Downloads\\d")]

for x in onlyfiles:
    if x.startswith("data"):
        y = x.split("data")
        os.rename(r'C:\\Users\\EGEMEN\\Downloads\\d\\' + x, r'C:\\Users\\EGEMEN\\Downloads\\d\\' + y[1])