The launcher or my computer?

[Elikadam]

So, I am pressing play. It acts like it is going to start up and load but after a few seconds it goes back to the launcher and says play again. I am unsure if it is my laptop or the launcher itself. I uninstalled and reinstalled the launcher, the mod packs and updated and restarted my laptop. 

I play on a mac OSX, it has 4 GB Ram and more than enough memory space. If I could get some help to understand why its doing this id be grateful cause i was playing just fine yesterday. 

 

Thank you guys in advance, i know your super busy so when you have time to help id be thankful.

[Amarnra]

Is the modpack you are trying to play a 1.7.10 modpack?

 

If so, me and two others also have the exact same issues. If you were to go into the modpack's logs folder, in the latest log you may find the following error:

java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.7.0_75]
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.7.0_75]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.7.0_75]
    at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.7.0_75]
    at net.minecraft.launchwrapper.Launch.launch(Launch.java:135) [launchwrapper-1.12.jar:?]
    at net.minecraft.launchwrapper.Launch.main(Launch.java:28) [launchwrapper-1.12.jar:?]
Caused by: java.lang.NullPointerException
    at net.minecraft.client.main.Main.main(SourceFile:116) ~[Main.class:?]
    ... 6 more