If you are looking for a copy of your retirement accounts from your previous or current employer start by contacting the company's Human Resources department. They should be able to send you in the right direction.
It will depend upon which type of account it is, but generally speaking you will want to find out who the custodian of your account is. If it is a 401K or other employer sponsored plan, you can speak with your Human Resources Department and/or the plan administrator. If it is a personal account you should call the broker/dealer or other custodian. You can then get in touch with them and request access to your account information or ask them to send you an account statement by mail. If you are still having trouble, you could contact a financial adviser for assistance.