Any refund will depend on the type of fare purchased and associated cancellation fees. You read and understood the fineprint....right?

Does the cancellation of yr friends ticket mean that travel insurance could assist?

Did you book online with THAI, or was it done through a TA. You should pursue the refund with whomever it was purchase from.

If from THAI online, they will credit the CCrd used for the purchase. This can take up to 6 weeks, although I've also had refunds completed on the spot (in Bangkok though, after some polite discussion on how it could be done in much less time than 6 weeks....)