If you have noticed your ad has disappeared the first thing you should do is go to the top of the For Sale/Wanted section and read the classifieds rules. Most likely you didn't include your location (or didn't include it properly) or have not properly introduced yourself in the introductions forum. I typically remove the offending post if it is your first offense and hope you realize what you did wrong and repost with the issue corrected. However, most people don't get the hint and repost with the same issue.
Subsequent issues result in warn points. If you acquire enough warn points your posting privileges are suspended. Since most issues in this section are related to failure to post your location I suggest you add your location to your profile so that it is always there and you no longer have to think about it.
Subsequent issues result in warn points. If you acquire enough warn points your posting privileges are suspended. Since most issues in this section are related to failure to post your location I suggest you add your location to your profile so that it is always there and you no longer have to think about it.