Fatal error launching game

i tried to start my minecraft and it would freeze the computer, then would unfreeze but would do nothing and in the development code it said

java.io.FileNotFoundException: File '/Users/user/Library/Application Support/minecraft/assets/indexes/1.7.3.json' does not exist
	at org.apache.commons.io.FileUtils.openInputStream(FileUtils.java:299) ~[launcher.jar:?]
	at org.apache.commons.io.FileUtils.readFileToString(FileUtils.java:1711) ~[launcher.jar:?]
	at net.minecraft.launcher.GameLauncher.getAssetObject(GameLauncher.java:323) ~[launcher.jar:?]
	at net.minecraft.launcher.GameLauncher.launchGame(GameLauncher.java:245) ~[launcher.jar:?]
	at net.minecraft.launcher.GameLauncher.onDownloadJobFinished(GameLauncher.java:616) [launcher.jar:?]
	at net.minecraft.launcher.updater.download.DownloadJob.popAndDownload(DownloadJob.java:120) [launcher.jar:?]
	at net.minecraft.launcher.updater.download.DownloadJob.access$000(DownloadJob.java:12) [launcher.jar:?]
	at net.minecraft.launcher.updater.download.DownloadJob$1.run(DownloadJob.java:89) [launcher.jar:?]
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:439) [?:1.6.0_65]
	at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303) [?:1.6.0_65]
	at java.util.concurrent.FutureTask.run(FutureTask.java:138) [?:1.6.0_65]
	at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895) [?:1.6.0_65]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918) [?:1.6.0_65]
	at java.lang.Thread.run(Thread.java:695) [?:1.6.0_65]