Help with LG Optimus L9

[Android Question]

I accidently deleted my default download manager. On my LG Optimus L9. Can anyone please help me with this I've been doing all I can do to restore it. I can't download any apps from the play store. When I open up play store it won't open up, it would open then automatically close down. Can anyone please help with this. Message me naun516@gmail.com