Minecraft not launching and freezing during load-up

When I open Minecraft Launcher there's no issue, then I hit play and the white screen with the red word Java pops up then loads to about 9/10 of the loading bar and freezes. From there I can not open any other tabs or even exit out of the application, I am forced to restart my laptop, which closes it. I have already launched AND restarted my laptop about seven times in my attempts to launch, and play Minecraft. I have not tried uninstalling and re-installing as I do not want to lose all of my worlds. If I must uninstall and re-install I will but I'd prefer not to. Please help me.