I'm 21 year old and from yesterday evening sudden cold in my legs and hands freezing and very pain my both legs and hands with back pain and body pain with a fever inside me y.??

Sorry to be late in answering. You’re likely better by now or already have been diagnosed by a health care worker near you. Suddenly feeling cold and at the same time feeling pain suggests an infection with activating your immune system resulting in fever. Feeling cold as you describe can be a rising temperature inside your body in an effort to defeat an infection. I hope you’re better by now.