I tried everything, redownloaded forge, I removed that reinstalled mine craft and downloaded forge, I even used a different computer.

don't tell me it was the mods I was using because even without mods it doesn't work. please help. :'( :'(

You'll probably have a crash report, if so it will be found in %appdata%/.minecraft/crash-reports if not you'll at least have a log found in %appdata%/.minecraft/logs/fml-client-latest.log

 

Post those here.

there is no crash report but there was a log here it is

 

[09:14:52] [main/INFO] [FML/]: Forge Mod Loader version 7.2.217.1147 for Minecraft 1.7.2 loading

[09:14:52] [main/INFO] [FML/]: Java is Java HotSpot 64-Bit Server VM, version 1.8.0_25, running on Windows 7:amd64:6.1, installed at C:\Program Files (x86)\Minecraft\runtime\jre-x64\1.8.0_25

[09:14:52] [main/DEBUG] [FML/]: Java classpath at launch is C:\Users\User\AppData\Roaming\.minecraft\libraries\net\minecraftforge\forge\1.7.2-10.12.2.1147\forge-1.7.2-10.12.2.1147.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\net\minecraft\launchwrapper\1.9\launchwrapper-1.9.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\org\ow2\asm\asm-all\4.1\asm-all-4.1.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\org\scala-lang\scala-library\2.10.2\scala-library-2.10.2.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\org\scala-lang\scala-compiler\2.10.2\scala-compiler-2.10.2.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\java3d\vecmath\1.3.1\vecmath-1.3.1.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\net\sf\trove4j\trove4j\3.0.3\trove4j-3.0.3.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\com\ibm\icu\icu4j-core-mojang\51.2\icu4j-core-mojang-51.2.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\net\sf\jopt-simple\jopt-simple\4.5\jopt-simple-4.5.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\lzma\lzma\0.0.1\lzma-0.0.1.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\com\paulscode\codecjorbis\20101023\codecjorbis-20101023.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\com\paulscode\codecwav\20101023\codecwav-20101023.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\com\paulscode\libraryjavasound\20101123\libraryjavasound-20101123.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\com\paulscode\librarylwjglopenal\20100824\librarylwjglopenal-20100824.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\com\paulscode\soundsystem\20120107\soundsystem-20120107.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\io\netty\netty-all\4.0.10.Final\netty-all-4.0.10.Final.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\com\google\guava\guava\15.0\guava-15.0.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\org\apache\commons\commons-lang3\3.1\commons-lang3-3.1.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\commons-io\commons-io\2.4\commons-io-2.4.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\net\java\jinput\jinput\2.0.5\jinput-2.0.5.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\net\java\jutils\jutils\1.0.0\jutils-1.0.0.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\com\google\code\gson\gson\2.2.4\gson-2.2.4.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\com\mojang\authlib\1.3\authlib-1.3.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\org\apache\logging\log4j\log4j-api\2.0-beta9\log4j-api-2.0-beta9.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\org\apache\logging\log4j\log4j-core\2.0-beta9\log4j-core-2.0-beta9.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\org\lwjgl\lwjgl\lwjgl\2.9.0\lwjgl-2.9.0.jar;C:\Users\User\AppData\Roaming\.minecraft\libraries\org\lwjgl\lwjgl\lwjgl_util\2.9.0\lwjgl_util-2.9.0.jar;C:\Users\User\AppData\Roaming\.minecraft\versions\1.7.2-Forge10.12.2.1147\1.7.2-Forge10.12.2.1147.jar

[09:14:52] [main/DEBUG] [FML/]: Java library path at launch is C:\Users\User\AppData\Roaming\.minecraft\versions\1.7.2-Forge10.12.2.1147\1.7.2-Forge10.12.2.1147-natives-626346272517539

[09:14:52] [main/DEBUG] [FML/]: Enabling runtime deobfuscation

[09:14:52] [main/DEBUG] [FML/]: Instantiating coremod class FMLCorePlugin

[09:14:52] [main/DEBUG] [FML/]: Added access transformer class cpw.mods.fml.common.asm.transformers.AccessTransformer to enqueued access transformers

[09:14:52] [main/DEBUG] [FML/]: Enqueued coremod FMLCorePlugin

[09:14:52] [main/DEBUG] [FML/]: Instantiating coremod class FMLForgePlugin

[09:14:52] [main/DEBUG] [FML/]: Added access transformer class net.minecraftforge.transformers.ForgeAccessTransformer to enqueued access transformers

[09:14:52] [main/DEBUG] [FML/]: Enqueued coremod FMLForgePlugin

[09:14:52] [main/DEBUG] [FML/]: All fundamental core mods are successfully located

[09:14:52] [main/DEBUG] [FML/]: Discovering coremods

[09:14:52] [main/INFO] [LaunchWrapper/]: Loading tweak class name cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker

[09:14:52] [main/INFO] [LaunchWrapper/]: Loading tweak class name cpw.mods.fml.common.launcher.FMLDeobfTweaker

[09:14:52] [main/INFO] [LaunchWrapper/]: Calling tweak class cpw.mods.fml.common.launcher.FMLInjectionAndSortingTweaker

[09:14:52] [main/ERROR] [LaunchWrapper/]: Unable to launch

java.util.ConcurrentModificationException

at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901) ~[?:1.8.0_25]

at java.util.ArrayList$Itr.remove(ArrayList.java:865) ~[?:1.8.0_25]

at net.minecraft.launchwrapper.Launch.launch(Launch.java:117) [launchwrapper-1.9.jar:?]

at net.minecraft.launchwrapper.Launch.main(Launch.java:28) [launchwrapper-1.9.jar:?]

 

I know minecraft 1.6.4 used to have issues with java 8 (There was recently a fix for it), I'm not sure about 1.7.2, you should try the latest forge for 1.7.10 (or 1. and see what happens.

thanks that actually worked but the reason I sent the 1.7.2 was because I wanted to play a modpack (its only 1.7.2.) because it was not working I tried without the mods and it still didn't work. so please tell me a way to fix it.