What is the ruling on someone who intended to perform Umrah, donned the Ihram garments, but was unable to go due to transportation issues, and is unsure whether he uttered the intention for Umrah? And what must he do to absolve himself?

Assuming the intention to enter the ritual (Nusuk) is made in the heart, Ihram is not valid merely by wearing the garments or reciting the Talbiyah. If you doubt your intention to enter the Nusuk, the default is that Ihram has not occurred, and nothing is binding upon you.

However, if you are certain that you intended to enter the Nusuk and then rejected your Ihram: - If you performed another Umrah or Hajj thereafter, it takes its place, or you become a Qarin (performing both Hajj and Umrah together), and the sacrifice of Qiran becomes obligatory upon you. - If you did not do that, you must go to Makkah to perform the Nusuk and exit Ihram. You are excused for the Ihram prohibitions you committed due to your ignorance, except for acts of destruction like cutting hair or trimming nails. For these, it is more cautious to offer a compensatory sacrifice with the option of choice (feeding six needy people, sacrificing a sheep, or fasting for three days).