That doesn't look like an ordinary IC.
You say no LED lights up now. Is that an LED that broke off?
Because if the led is intact on the board, then perhaps your USB connector has a cracked solder joint? Or there's a broken trace that carries power?
So maybe the part that broke off carries power. But then it ought to have more durable pins connecting it.
Can you make a sharper closeup photo? There may be indentations in the solder pads that match something on the broken off piece.
Also a closeup of the other side of the board.
I've never opened a pen drive so this is all conjecture by me.
---------- Post added at 18:08 ---------- Previous post was at 17:34 ----------
And it's true the broken-off part doesn't look like an ordinary LED. It appears to have 4 pins.
But it does look like a translucent white piece that might cover one or two LED's shining through to the outside. One Led showing power, another showing activity. Needing 4 pins?
What windows (translucent or otherwise) are on the housing pieces?
And can you measure a 5V power reading on the board?