It's a little difficult to offer any help based on the minimal information you've provided.
What version of MB are you using? (Help > About) INCLUDE THE LETTER (if any) AFTER THE NUMBER
How was MB installed? (Store, Installer, Portable)
Does MB eventually open?
If so, is there anything in the error log? (Help > Support > View Error Log
If so, copy/paste it here. Do not paste the entire log. Start with the date/time closely related to when you opened MB and the error occurred.