How to “glue” back a very very small piece of glass to my window?

1) On the outside of the window glass, there is a pin size hole.
2) On the inside, the very very small piece of broken off glass has a diameter of 1/4 inch.
3) If I cannot “glue” it back, can I use a “glass filler”? Is there such a thing as “glass filler” (as in wood filler) ?