My Minecraft in 1.8 runs perfectly, but when I try other versions, like 1.7.10, it doesn't work. I get a bunch of errors in the launcher.
I want 1.7.10 back, so I can re-install minecraft forge, I upgraded the computer to windows 8.1, and I lost about half of my MC files for some reason. I need it to work again. Here are the errors.

Game Output
Exception in thread "main" java.lang.NoClassDefFoundError: io/netty/buffer/ByteBufOutputStream
at bao.<init>(SourceFile:110)
at net.minecraft.client.main.Main.main(SourceFile:129)
Caused by: java.lang.ClassNotFoundException: io.netty.buffer.ByteBufOutputStream
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 2 more
Java HotSpot(TM) Client VM warning: Using incremental CMS is deprecated and will likely be removed in a future release

Launcher Log
[09:39:50 INFO]: Job 'Version & Libraries' finished successfully (took 0:00:02.250)
[09:39:50 INFO]: Launching game
[09:39:50 INFO]: Unpacking natives to C:\Users\Laptop\AppData\Roaming\.minecraft\versions\1.7.10\1.7.10-natives-6520704258636
[09:39:52 INFO]: Launching in C:\Users\Laptop\AppData\Roaming\.minecraft
[09:39:52 INFO]: Half command: C:\Program Files\Java\jre1.8.0_45\bin\javaw.exe -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M -Djava.library.path=C:\Users\Laptop\AppData\Roaming\.minecraft\versions\1.7.10\1.7.10-natives-6520704258636 -cp C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\com\mojang\realms\1.3.5\realms-1.3.5.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\org\apache\commons\commons-compress\1.8.1\commons-compress-1.8.1.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\org\apache\httpcomponents\httpclient\4.3.3\httpclient-4.3.3.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\commons-logging\commons-logging\1.1.3\commons-logging-1.1.3.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\org\apache\httpcomponents\httpcore\4.3.2\httpcore-4.3.2.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\java3d\vecmath\1.3.1\vecmath-1.3.1.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\net\sf\trove4j\trove4j\3.0.3\trove4j-3.0.3.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\com\ibm\icu\icu4j-core-mojang\51.2\icu4j-core-mojang-51.2.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\net\sf\jopt-simple\jopt-simple\4.5\jopt-simple-4.5.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\com\paulscode\codecjorbis\20101023\codecjorbis-20101023.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\com\paulscode\codecwav\20101023\codecwav-20101023.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\com\paulscode\libraryjavasound\20101123\libraryjavasound-20101123.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\com\paulscode\librarylwjglopenal\20100824\librarylwjglopenal-20100824.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\com\paulscode\soundsystem\20120107\soundsystem-20120107.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\io\netty\netty-all\4.0.10.Final\netty-all-4.0.10.Final.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\com\google\guava\guava\15.0\guava-15.0.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\org\apache\commons\commons-lang3\3.1\commons-lang3-3.1.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\commons-io\commons-io\2.4\commons-io-2.4.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\commons-codec\commons-codec\1.9\commons-codec-1.9.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\net\java\jinput\jinput\2.0.5\jinput-2.0.5.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\net\java\jutils\jutils\1.0.0\jutils-1.0.0.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\com\google\code\gson\gson\2.2.4\gson-2.2.4.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\com\mojang\authlib\1.5.21\authlib-1.5.21.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\org\apache\logging\log4j\log4j-api\2.0-beta9\log4j-api-2.0-beta9.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\org\apache\logging\log4j\log4j-core\2.0-beta9\log4j-core-2.0-beta9.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\org\lwjgl\lwjgl\lwjgl\2.9.1\lwjgl-2.9.1.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\org\lwjgl\lwjgl\lwjgl_util\2.9.1\lwjgl_util-2.9.1.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\libraries\tv\twitch\twitch\5.16\twitch-5.16.jar;C:\Users\Laptop\AppData\Roaming\.minecraft\versions\1.7.10\1.7.10.jar net.minecraft.client.main.Main
[09:39:52 INFO]: Looking for orphaned versions to clean up...
[09:39:52 INFO]: Looking for old natives & assets to clean up...
[09:39:56 ERROR]: Game ended with bad state (exit code 1)
[09:39:56 INFO]: Ignoring visibility rule and showing launcher due to a game crash
[09:39:56 INFO]: Deleting C:\Users\Laptop\AppData\Roaming\.minecraft\versions\1.7.10\1.7.10-natives-6520704258636
[09:39:56 WARN]: Couldn't delete C:\Users\Laptop\AppData\Roaming\.minecraft\versions\1.7.10\1.7.10-natives-6520704258636 - scheduling for deletion upon exit