Starting Minecraft the Development Console states that there is an error and report it to Mojang

Put the summary of the bug you're having here

What I expected to happen was...:
Minecraft Starting

What actually happened was...:
Dev. console states this: Fatal error launching game. Report this to http://mojang.atlassian.net please!
java.lang.RuntimeException: Classpath file not found: C:\Users\Margaret\AppData\Roaming\.minecraft\libraries\com\mojang\realms\1.2.5\realms-1.2.5.jar
at net.minecraft.launcher.GameLauncher.constructClassPath(GameLauncher.java:590)
at net.minecraft.launcher.GameLauncher.launchGame(GameLauncher.java:418)
at net.minecraft.launcher.GameLauncher.onDownloadJobFinished(GameLauncher.java:691)
at net.minecraft.launcher.updater.download.DownloadJob.popAndDownload(DownloadJob.java:124)
at net.minecraft.launcher.updater.download.DownloadJob.access$000(DownloadJob.java:15)
at net.minecraft.launcher.updater.download.DownloadJob$1.run(DownloadJob.java:94)
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
at java.util.concurrent.FutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

Steps to Reproduce:
1. Login
2. Click Play
3. Go to development console(I didn't touch the .minecraft folder ever.