The speaker wakes up one day feeling that their own self, "I," has gone missing. It's a funny, almost childlike opening, since they check the bag and the pockets as if the self were a set of keys. But the search quickly turns serious. They look deep inside, examine every part, and still can't see "I." The repeated word makes the lines feel dizzy, like looking for something with the very thing that's lost.
The mood shifts when the speaker, desperate, looks up and sees "lots of me" in the market, on the bus, in other people's eyes. The suggestion is that the self isn't hidden away inside but scattered among the people around us, or perhaps reflected back by them. The ending trails off with "And the I ...", leaving the answer open. The speaker may be about to find themselves, or may be realizing that the self can't be pinned down. The feeling moves from confusion and worry toward a quiet, uncertain wonder.