My minecraft wont start. This error pops up. Plz Help

[JordyJordo]

[b][20:33:02] [main/INFO] [LaunchWrapper]: Loading tweak class name cpw.mods.fml.common.launcher.FMLTweaker
[20:33:02] [main/INFO] [LaunchWrapper]: Using primary tweak class name cpw.mods.fml.common.launcher.FMLTweaker
[20:33:02] [main/INFO] [LaunchWrapper]: Calling tweak class cpw.mods.fml.common.launcher.FMLTweaker
[20:33:02] [main/INFO] [FML]: Forge Mod Loader version 7.10.85.1236 for Minecraft 1.7.10 loading
[20:33:02] [main/INFO] [FML]: Java is Java HotSpot(TM) 64-Bit Server VM, version 1.8.0_25, running on Windows 8.1:amd64:6.3, installed at C:\Program Files (x86)\Minecraft\runtime\jre-x64\1.8.0_25
[20:33:03] [main/INFO] [LaunchWrapper]: Loading tweak class name cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker
[20:33:03] [main/INFO] [LaunchWrapper]: Loading tweak class name cpw.mods.fml.common.launcher.FMLDeobfTweaker
[20:33:03] [main/INFO] [LaunchWrapper]: Calling tweak class cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker
[20:33:03] [main/INFO] [LaunchWrapper]: Calling tweak class cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker
[20:33:03] [main/INFO] [LaunchWrapper]: Calling tweak class cpw.mods.fml.relauncher.CoreModManager$FMLPluginWrapper
[20:33:06] [main/INFO] [FML]: Found valid fingerprint for Minecraft Forge. Certificate fingerprint e3c3d50c7c986df74c645c0ac54639741c90a557
[20:33:06] [main/ERROR] [FML]: The minecraft jar file:/C:/Users/Jordan/AppData/Roaming/.minecraft/versions/1.7.10-Forge10.13.2.1236/1.7.10-Forge10.13.2.1236.jar!/net/minecraft/client/ClientBrandRetriever.class appears to be corrupt! There has been CRITICAL TAMPERING WITH MINECRAFT, it is highly unlikely minecraft will work! STOP NOW, get a clean copy and try again!
[20:33:06] [main/ERROR] [FML]: For your safety, FML will not launch minecraft. You will need to fetch a clean version of the minecraft jar file
[20:33:06] [main/ERROR] [FML]: Technical information: The class net.minecraft.client.ClientBrandRetriever should have been associated with the minecraft jar file, and should have returned us a valid, intact minecraft jar location. This did not work. Either you have modified the minecraft jar file (if so run the forge installer again), or you are using a base editing jar that is changing this class (and likely others too). If you REALLY want to run minecraft in this configuration, add the flag -Dfml.ignoreInvalidMinecraftCertificates=true to the 'JVM settings' in your launcher profile.
Exception in thread "main" [20:33:06] [main/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStreamrintln:748]: java.lang.ExceptionInInitializerError
[20:33:06] [main/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStreamrintln:748]: at cpw.mods.fml.common.asm.FMLSanityChecker.call(FMLSanityChecker.java:159)
[20:33:06] [main/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStreamrintln:748]: at cpw.mods.fml.common.asm.FMLSanityChecker.call(FMLSanityChecker.java:39)
[20:33:06] [main/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStreamrintln:748]: at cpw.mods.fml.relauncher.CoreModManager$FMLPluginWrapper.injectIntoClassLoader(CoreModManager.java:126)
[20:33:06] [main/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStreamrintln:748]: at net.minecraft.launchwrapper.Launch.launch(Launch.java:115)
[20:33:06] [main/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStreamrintln:748]: at net.minecraft.launchwrapper.Launch.main(Launch.java:28)
[20:33:06] [main/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStreamrintln:748]: Caused by: java.lang.NullPointerException
[20:33:06] [main/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStreamrintln:748]: at cpw.mods.fml.common.Loader.<init>(Loader.java:182)
[20:33:06] [main/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStreamrintln:748]: at cpw.mods.fml.common.Loader.instance(Loader.java:160)
[20:33:06] [main/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStreamrintln:748]: at cpw.mods.fml.common.FMLCommonHandler.<init>(FMLCommonHandler.java:87)
[20:33:06] [main/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStreamrintln:748]: at cpw.mods.fml.common.FMLCommonHandler.<clinit>(FMLCommonHandler.java:77)
[20:33:06] [main/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStreamrintln:748]: ... 5 more
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[Dark Lord of Tech]

Won't launch due to some modification done to the software \ game.

 

[tman1]

"The minecraft jar file:/C:/Users/Jordan/AppData/Roaming/.minecraft/versions/1.7.10-Forge10.13.2.1236/1.7.10-Forge10.13.2.1236.jar!/net/minecraft/client/ClientBrandRetriever.class appears to be corrupt!"

first try reinstalling forge

 

[HDMI703]

Post this thread to minecraft forums they will help you more