So basicly you blew up a spawner yea? Its gone, But If You Want You Can Cheat It In!
MAKE SURE COMMANDS ARE ON:
Do /gamemode c
then type: /give @p mob_spawner
Then get a spawn egg, place the mob spawner and press on it with the spawn egg of your choice!
IF COMMANDS ARE NOT ON:
Press Esc, Open To Lan, Press Enable Cheats, Done, The Do What I Said Above.