So, I believe i totally killed it now. I put the META-INF folder back into the minecraft.jar and it loaded to the screen where you choose single player, multiplayer etc. But i get the "dirt screen" when i try to start single player. And this was in the log:
13-06-09 22:07:50 [sEVERE] [ForgeModLoader] Fatal errors were detected during the transition from AVAILABLE to SERVER_STOPPED. Loading cannot continue
2013-06-09 22:07:50 [sEVERE] [ForgeModLoader]
mcp{7.44} [Minecraft Coder Pack] (minecraft.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available
FML{5.2.21.729} [Forge Mod Loader] (coremods) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available
Forge{7.8.0.729} [Minecraft Forge] (coremods) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available
2013-06-09 22:07:50 [sEVERE] [ForgeModLoader] The ForgeModLoader state engine has become corrupted. Probably, a state was missed by and invalid modification to a base classForgeModLoader depends on. This is a critical error and not recoverable. Investigate any modifications to base classes outside ofForgeModLoader, especially Optifine, to see if there are fixes available.
2013-06-09 22:07:50 [iNFO] [sTDERR] Exception in thread "Server thread" java.lang.RuntimeException: The ForgeModLoader state engine is invalid