I recommend that you call a Title Company (Ticor, First American) - Ask to speak with a Title Officer. Supply the address of the home and they will pull the lien/s and tell you how to clear it. They are very helpful .
Don't do this on your own as when you sell your home you will need it to clear title and if you don't do it right they won't insure the title anyway. They won't charge you to steer you I the right direction and they are the professionals.
Being a Broker when we encounter a lien on title or a problem we immediately contact our title officer for advice. In some cases there even security bonds that can be purchased when a lien holder disappears or you can prove payment has been satisfied.
If you are re-financing or selling, your escrow and/or title company should be able to tell you who now holds the note on your property. Give them a copy of your latest mortgage statement and they will easily find out who now owns it.
If the lien you refer to is not a mortgage lender - that's an entirely different problem. Larry and Michael are right, you may have to go to court to get a release of the lien ordered by a judge because there is no one around to accept payment and release the lien. A good example is a mechanics or supplier's lien. For either, you need an attorney to research the lien and go to court for you to eliminate the lien by function of law.
Best of luck.