Minecraft is crashing on startup.

My minecraft crashes whenever I try to open it.  It loads 75%, freezes and show these weird symbols - ▯▯▯▯▯    ▯▯▯▯▯. This has happen to many times. When I do a bunch of random things like reinstalling java, reinstalling the launcher and it gets fixed. But now its not working.Please help me out with this problem.