TheFatElf

I fixed my problem, thanks for this guys I had to do it multiple times before it worked though!

I've renamed the file "minecraft_1.2.5" (and I've tried "minecraft_1.2.5.jar", just in case), and it's in AppData/Roaming/.techniclauncher/cache

Yeah, it just did the exact same thing

Nope, no luck. It's definitely already a .jar file, so that's just made it ".jar.jar", which as you guys said is wrong anyway.

Right, I have this issue, and I've tried all the solutions suggested here. I've downloaded the .jar with Chrome, renamed it "minecraft_1.2.5" (it's definitely a .jar file, not a .zip), placed it in the cache folder and it changed nothing. I've checked, double checked and checked again the name of the file, it's DEFINITELY right. Please help before I break my laptop.