I fell ill and couldn't complete the pilgrimage. What now?

Being prevented from completing a pilgrimage after entering ihrām has its own name in fiqh — ihsār — and its own verse:

“And complete the ḥajj and ʿumrah for Allah. But if you are prevented, then offer what can be obtained with ease of sacrificial animals. And do not shave your heads until the sacrificial animal has reached its place of slaughter. And whoever among you is ill or has an ailment of the head making shaving necessary must offer a ransom of fasting three days or charity or sacrifice. And when you are secure, then whoever performs ʿumrah during the ḥajj months followed by ḥajj offers what can be obtained with ease of sacrificial animals. And whoever cannot find or afford such an animal - then a fast of three days during ḥajj and of seven when you have returned home. Those are ten complete days. This is for those whose family is not in the area of al-Masjid al-Ḥarām. And fear Allah and know that Allah is severe in penalty.” (Qur’an 2:196)

So the framework exists in the text: a person prevented offers what is available as a sacrifice, and is released from ihrām rather than left suspended in it.

What your specific answer turns on:

1. Whether you made a condition at the start. Someone who says, on entering ihrām, that their release is wherever they are prevented, is released without an offering. Whether you did this is often the single fact that decides the whole question — and it is why guides advise saying it. 2. Hajj or ‘Umra. The consequences differ, since Hajj is time-bound to specific days and ‘Umra is not. 3. What you had already completed when you were stopped. 4. Whether it was your obligatory Hajj or a voluntary one. An obligatory Hajj that was not completed remains owed if you later become able again.

And the governing principle over all of it: “Allah does not charge a soul except with that within its capacity. It will have the consequence of what good it has gained, and it will bear the consequence of what evil it has earned. "Our Lord, do not impose blame upon us if we have forgotten or erred. Our Lord, and lay not upon us a burden like that which You laid upon those before us. Our Lord, and burden us not with that which we have no ability to bear. And pardon us; and forgive us; and have mercy upon us. You are our protector, so give us victory over the disbelieving people."” (Qur’an 2:286)

Because the answer changes completely on facts only you have, this is one to put to a scholar — and if it happened at Hajj itself, to one of the scholars present there, who handle exactly this every season and can settle it on the spot.

One thing that needs no ruling: falling ill is not a failure, and there is no blame attached to a body that gave out. The reward for what was intended and attempted is not withdrawn because it could not be finished.