The Minecraft Launcher Wont open

this was what is said when it "crashed"

java.lang.NoClassDefFoundError: org/apache/logging/log4j/core/config/XMLConfiguration$Status
at org.apache.logging.log4j.core.config.XMLConfiguration.constructHierarchy(XMLConfiguration.java:313)
at org.apache.logging.log4j.core.config.XMLConfiguration.constructHierarchy(XMLConfiguration.java:307)
at org.apache.logging.log4j.core.config.XMLConfiguration.setup(XMLConfiguration.java:271)
at org.apache.logging.log4j.core.config.BaseConfiguration.start(BaseConfiguration.java:140)
at org.apache.logging.log4j.core.LoggerContext.setConfiguration(LoggerContext.java:339)
at org.apache.logging.log4j.core.LoggerContext.reconfigure(LoggerContext.java:378)
at org.apache.logging.log4j.core.LoggerContext.start(LoggerContext.java:149)
at org.apache.logging.log4j.core.impl.Log4jContextFactory.getContext(Log4jContextFactory.java:85)
at org.apache.logging.log4j.core.impl.Log4jContextFactory.getContext(Log4jContextFactory.java:34)
at org.apache.logging.log4j.LogManager.getLogger(LogManager.java:387)
at org.apache.logging.log4j.LogManager.getLogger(LogManager.java:322)
at net.minecraft.launcher.Launcher.<clinit>(Launcher.java:56)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at net.minecraft.bootstrap.Bootstrap.startLauncher(Bootstrap.java:240)
at net.minecraft.bootstrap.Bootstrap.execute(Bootstrap.java:124)
at net.minecraft.bootstrap.Bootstrap.main(Bootstrap.java:381)
Caused by: java.lang.ClassNotFoundException: org.apache.logging.log4j.core.config.XMLConfiguration$Status
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 19 more