Hi Liz, It sounds like you have done everything that one would in order to get your signal back.
If you have done a full factory reset and you know your sim is working in another handset, I think it is worth doing the sim change in both directions. In other words does your Samsung work with your daughters sim card?
If not and if your phone is unlocked try a sim from a different network. If you still have no results and you have cleaned the sim slot contacts, double checked all settings (although the reset should have done that) for something too obvious that has been changed by mistake , I am afraid it's not looking good for your phone and it is probably a visit to a phone shop (is it still under guarantee or insured?)