1999 Volvo S80 ignition key will not turn, as a result car will not start.

Have her turn the steering wheel in case tires are binding against a curb/parking block. Try another spare key, If that doesn't work will probably have to replace the ign/key lock cylinder.

tell her to kindly make sure the vehicle is in park all the way befor turning the key and not to force it ..as it may break..if it still does not turn then it may either be key problem.(wrong key)or the ignition cylinder.