You cannot trace a sim card , but you can trace the imei number of the phone. You can go to your cell phone provider and see what help they can provide or recomend.
If you have lost your sim card and it wasn't in your phone then it could not be traced unless it was put in a phone and powered up and then someone took it to a cell phone carrier to try and use. So it would be a good idea to contact your cell hone company.
Sim go for about $5 on ebay so they are not expensive and worth the trouble to try and find it.