My daughter is 19 years old and wants to know if she can file for back child support. Her father lives in Costa Rica and never helped her mother or saw the child after the age of 7 until she was 18.

No. She can not. Child support is owed to the custodial parent, not the child.

You might have been able to file, but retroactive (back) child support is not allowed in many states. In addition, you may have a statute of limitations to deal with.

Finally, if he lives in Costa Rica, how do you imagine you would collect it?

If you wanted child support, you should have thought about this 19 years ago.

Just out of curiosity, which State are YOU living in?

The child can not file,

Did the mother ever file ? Since normally there is no "back" support unless there was an order for support that was not paid, ( a few states allow back at time of filing)

But the mother of the child is the one that has to file and go after child support