I can’t login into my iCloud

From which device you are trying to access www.icloud.com is it a Mac / browser ( what is the operating system and their version ) it all depends what correct credentials do you have in records .

If the account is set up with two factor authentication have you added working trusted devices to get the code , is Apple ID address and password correct .

See the article If you can't connect or sign in to iCloud - Apple Support