Final Cut Pro X crashing I'm trying to open up a library in Final Cut Pro , it used to work fine and now everytime i open it up it crashes the entire application , 
I have a Mac Pro running Yosemite , i tried multiple solutions as restoring it from a back up everytime i load it crashes i even tried going back 6 months ago and still it crashes , 
when i open a new library from scratch it works fine 
the only thing i didnt try is to remove the application and reinstall it , but i dont think doing that will help , please assist 
Thanks !!!
Apple have released a recent update to FCPX, 10.2.3 which fixes lots of issues like this. I would recommended this update first as it has solved crashing issues for me.

https://support.apple.com/en-gb/HT201237

Sometimes FCPX doesn't like it when your library is saved separately to user/movies/ perhaps try moving the library there and see if it helps. 

Also media from multiple drives can cause issues if FCP get's stuck trying to link some. If any media is stored on external drives, are they fast drives i.e. thunderbolt, USB3, firewire 800? Potentially FCPX is getting stuck trying to locate the media and can't connect to everything properly. Perhaps try moving media to a reliable drive to try it out like your system drive.

Hope that helps.