The Sawm is valid and the forgotten Salah must be made up for.
It is not obligatory to make up for the missed Tarawih because it is a supererogatory Salah. If the person offers supererogatory Salah during the day according to their ability, this will be better. Whenever the Prophet (peace be upon him) missed Qiyam-ul-Layl (optional Prayer at night) due to sleeping or illness, he used to make up for it during the day. In case of offering Witr (Prayer with an odd number of units) during the day, only two Rak`ahs (unit of Prayer) should be offered.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.