The most general answer has to be, the applicable law may change depending upon which court is asked the question. If multiple overseas countries not otherwise specified are potentially involved, no one can guess in the abstract what those courts, asked to determine what law applies, will determine.
You would have to get a court that has jurisdiction over the defendant and the defendant's assets. The foreign court may have jurisdiction over the defendant, but if there are no assets there to attach, and the defendant does not pay the judgment (assuming your friend gets one), then you would have to have the judgment accepted by a US court. Suing the defendant in a court with jurisdiction over the defendant's HQ might be the best way to ensure a judgment would be satisfied with minimal additional costs.
If the contract is silent on a choice of law, typically it would be the laws of the jurisdiction in which the contract was formed. If your friend signed the contract in the US and then went over seas, that is a strong argument for US laws being applicable.
This is not child's play. Your friend should get an attorney to advise them on this.
I agree with Mr. Schrafel. If the contract was formed in the US, your friend may need to file suit in the US. If the company is located in the US, your friend should probably sue the company wherever the company is located. Your friend should consult with an attorney regarding the particulars of her case. Many attorneys on here, including myself, offer free initial consultations.
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