I have a big problem because it happened with my toyota 1990 4 runner motor 3.0
I was cleaning the fuel injectors and the fuel injector grommet was very worn so when
Iwas to take off it broke by itself and a piece of it felt down into the grommet hole so my question is will there be any problem because of it or there some things to fix this problem please I need some addvice about it. Thanks

Remove the injector. Using a LED flashlight, and a pair of long tweasers, reach down and recover the broken grommet.

If it becomes impossible to remove, take out the spark plug on that cylinder and start it up for several secs.
The fast escaping air will puff it out. I really don't think you're in serious trouble here.

Try to vacuum it out, if its down inside the fuel rail( if that model has it) it will just come back and clog another injector. Also try a retrival claw tool like so http://www.faucetdirect.com/imagebase/resized/330x320/permaflowimages/draper-claw-pick-up-tool-610mm.jpg