Orihime does not exactly “come back to life” in the sense of dying and being resurrected. In Bleach , her power, Soten Kisshun, is better understood as rejection : she can reject harm, damage, and even a state of things, restoring someone or something to how it was before the injury.
That is why the confusion exists. Her ability can look like healing, but the series presents it as more than that. She is not simply mending wounds; she is undoing the event that caused them, which is why fans often describe it as reversing reality rather than healing in the usual sense.
The important limit is that this is not the same as reliably reviving the truly dead. The sources found here suggest she can restore severe injuries, even ones that seem fatal, but there is no solid support for a clean “bring anyone back from death” rule. In other words, if Orihime appears to “revive” someone, the safer reading is that the person was still within the reach of her rejection power, not that she resurrected an already gone soul.
A simple way to think about it is this: if a character is badly damaged, Orihime may be able to reject that damage. If a character is fully and permanently dead, the story does not clearly establish that she can undo that with certainty.
So the short answer is: Orihime does not literally come back to life; she uses a power that can reverse injuries so completely that it can look like resurrection.