launcher not letting me sign in

i just bought minecraft about a month ago and there hasnt been any problems until recently. first, the launcher wouldnt even start up. like it would load for a few seconds and then just stop. to try to fix that i uninstalled it and went to reinstall it and that got it to start up.. somewhat. now its just showing a screen asking for my email address/username and my password. but every time i enter those, it says 'invalid credentials' . and its not that any of this information is incorrect bc i checked sooo many times to make sure it was all right and i changed my password about 5 different times. i closed out of it, opened it back up. i shut down my computer, turned it back on. ive updated my computer as well. this has been consistent for about 2 weeks now. i did try to email mojang but they havent emailed me back. i dont really know what else to do