I can't play

Excuse me , i don't now my version

I can't to play because my game doesn't work ,he stays on the launcher or we can press play , but after this , a message appears :

in french : Erreur : impossible de trouver ou charger la classe principale net.minecraft.client.main.Main
Java HotSpot(TM) Client VM warning: Using incremental CMS is deprecated and will likely be removed in a future release

in Englisish : Error : unable to find or load the main class
net.minecraft.client.main.Main
Java HotSpot(TM) Client VM warning: Using incremental CMS is deprecated and will likely be removed in a future release

Please help me ,
Thanks, cordially