When Minecraft loads up sometimes the sound won't load with it even when my sound is all the way up.

If the launcher closes after game start, please edit your profile and select "Launcher visibility" then, "Keep the launcher open".

Also try the Mojang Support Center for technical support.

Please attach the complete output of the "Game Output (Your Minecraft name) " which can be found on the fourth tab of the launcher.

Ticket resolved as incomplete, because no answer in a reasonable amount of time (1+ year), if it still happens, please update the ticket.