Once you have downloaded minecraft 1.8 there is no way to uninstall it without uninstalling the whole game. You could revert to a previous version of Minecraft, but to do that you would first have to obtain the program files of the version you are trying to revert to. You may be able to find these files online, but that is doubtful since distributing any version of Minecraft online for free would be violation of copywrite law.
You can uninstall it in the list of programs.
Computer/Control Panel/Uninstall a program.
No, only if you delete your .minecraft folder, minecraft isn't 'installed' so you can't uninstall it either, just deleting it from your desktop does the trick, all your worlds will be left alone.
Nothing will happen if you keep installing and uninstalling Minecraft. Minecraft does not track how many times you have installed it nor does track how many computers you have it installed on. The only drawback is if you uninstall Minecraft by deleting the .minecraft folder you will lose all of your saved worlds on that computer.
One of the Minecraft files that are required to start it may be corrupted. Uninstall and reinstall Minecraft and see if that fixes it.
To uninstall a mod, start up the client and then click options and click force update, then login. It will reset Minecraft to default settings.
the easiest way to uninstall a minecraft mod (like single player commands) is to replace the jar file to do this 1.start minecraft.exe(starting minecraft in a web browser will not work) 2. select options 3.click force update 4. login and the minecraft jar files will redownload (you will still keep your saves and texture packs)
If you have a previous version of Minecraft, there should be a notification when you start the game and sign in telling you that you can update the game. If this doesn't come up, uninstall and reinstall the game and it should be updated.
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You don't need to unblock any just uninstall and install again.
You could either uninstall some programs you arent using or get a new computer with more RAM.
Have you port-forwarded? That's needed for Minecraft servers to work (and for most other gaming servers).