What is required if one omits a pillar (rukn) and does not know which unit it belonged to?

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If a pillar is omitted and its location is unknown, the ruling defaults to the worst-case scenario to ensure certainty. If one prostration is omitted and it is unknown if it was from the fourth rak'ah or an earlier one, it is treated as belonging to the earlier rak'ah, thus necessitating a full previous rak'ah. If it is counted as being from the fourth rak'ah, only one prostration is required. If two prostrations are omitted and it is unclear if they belong to two separate rak'ahs or one, they are assigned to two separate rak'ahs, thus requiring two full rak'ahs. If one knows a pillar was omitted in the current rak'ah but is unsure if it was bowing (ruku') or prostration (sujud), it is treated as bowing, necessitating the performance of bowing and everything subsequent to it.