Two cases might happen in your case -
1- If you have left recently in 1-2 years then you can't withdraw PF. On PF withdrwal form there are some details that has to be filled by the employer and his seal and attestation is required
2- If you have left more than 2 years then fill form 19 and 10C and submit to the PF office where you have account. Money will be credited to your account or cheque will be sent via Post.