[MCL-9747] Minecraft Crashed

Minecraft upgraded and now it crashes. I've attached the only logs I can find. Please help.

[0724/201831:INFO:GameCallbacks.cpp(193)] launcher/launcher (main) info Error occurred during initialization of VM
java/lang/ClassNotFoundException: error in opening JAR file C:\Program Files (x86)\Minecraft\runtime\jre-x64\1.8.0_51\lib\rt.jar