Maybe. It depends on your balance.

If you had a balance of more than $5000 you may find that the money is still in the plan. Contact your former employer to see if your account is still there and what your balance is. They are required to send you an annual statement so you should be getting one or they will want your correct address.

If you had a balance under $5000 you should know that the rules changed during the time you mentioned and the employer had the option to get rid of these small balances via distribution or ultimately by turning the money over to the state's escheatment program. That means after failing to find you they could turn over the money to the state who would try to find you. If that happened you can contact the state to see if the money is there.

A third option is that you were not vested in your account (0% vested). In that case, even though the money showed in your account it was never yours. When you terminated it would have gone back into the plan to be allocated to other employees or used to offset plan expenses.

I hope you find it!