How in the world can you be 24 and not know anything about periods?!? You really need to go talk to your mom because these questions all sound like they are coming from a 12 year old girl rather than a young woman.
No. I am getting the impression that you have never used a tampon and are afraid. That is normal. Just get a the smaller size and try to relax putting it in. Try one before swimming so you know what it feels like. One can never get lost inside, even if you forget to take one out and put the next one. (I haven't done it, but I know it has happened.) They really are no big deal.
It may be difficult for YOU to retrieve if a string breaks. In fairness, a tampon can get wedged in awkward ways if you try to retrieve it and can't grasp it. You may have to get a doctors help. I really don't know why everyone is giving you so much grief about this question. I've had this happen before. It's inconvenient and embarrassing when you really don't know what to do or who to ask.
Everyone who is saying "go talk to someone close to you" YOU WENT AND ANSWERED THE QUESTION!!!!!!! YOU COULD OF CHOSEN TO IGNORE IT!!!! SO DON'T COMPLAIN!!! Now I am not saying she hasn't, but maybe she hasn't got anyone close to her, that's why she asked us.
The opening of the cervix (located at the top of the vagina) is too tiny for a tampon to get through. So if you have a tampon inside, it is in your vagina, not further up. If you can't feel anything inside and haven't noticed any other symptoms (like a strange-colored or foul-smelling discharge or pain) it's unlikely that you have a tampon there.
If you think you might have left a tampon in and can't find it, see your doctor. He or she can do a more complete exam to look for the tampon. It is important to make sure to remember to take out tampons so that you don't get an infection. Don't be embarrassed about asking the doctor to take a look - lots of girls worry about forgotten tampons and they can lead to an infection if left in too long
Sometimes when your flow is light, it can be uncomfortable to put in a tampon. On those days, some girls find it more comfortable to use a pad.