Best place to start is with your employer and ask them to direct you to the person who handles Human Resources. Have a discussion with them regarding if you are eligible for the plan and/or a current participant if you are not sure. The type of retirement plan they have set up will be critical to understanding if you are eligible and have been participating in some way. If you have been putting a portion of your pay into the plan then you are a participant. They can direct you from there and they can eventually direct you on how to find out what you might have and how to get access to this information.