To what extent is the statement true that the deed of the disobedient (disobedient to God) is not accepted? Does this mean that his deed is not sufficient or that he receives no reward for it? And are his acts of worship, such as prayer, fasting, zakat, and Hajj, valid and sufficient?

Disrespecting parents is one of the major sins, exposing its perpetrator to Allah's wrath and anger. The one who disobeys parents is cursed, and Allah will not look at him on the Day of Resurrection, nor will he enter Paradise. Furthermore, disobeying them nullifies some good deeds, rendering them unacceptable for their doer, but it does not invalidate the validity of deeds themselves; rather, it is major shirk (associating partners with Allah) that invalidates them. Therefore, one must beware of disobeying parents and instead treat them with kindness and obey them in what is right.