I worked for a restaurant for 3 years and contributed to my 401 k for 2 years. I moved to a different state and the restaurant went out of business. I have looked on the National Registry for Unclaimed Retirement Benefits and found nothing. This happened about 15 years ago. Is there any way to find the missing money? I don't know what happened to the owners of the restaurant.

Remember that it's not the employer who manages your 401(k) acccount, but a plan administrator who is hired by the employer to manage the accounts. This would typically be a financial institustion such as a bank, insurance company, brokerage house, etc. Do you have copies of any of the old quarterly statements you should have been receiving for the past 15 years? On them you should be able to find a contact phone number for the plan administrator. If you haven't ben receivinbg statements then you may be considered "lost" "by the administrator. Try a search of the database of "unclaimed assets" that each state maintains - do a Google search using the name of the state and "unclaimed assets" and you should get to a web site that allows you to search on your name to see if any financial institutions have reported you as lost.