doesnt boot up

[johnnie 65]

my nexus 7 is rooted i downloaded a app to changed the fonts on my device i backed up like i should have it worked good the first time when i wanted to change the fonts again i rebooted now it doesnt boot past the colourful x for the past 15 mins i tried restarting but git the same thing wat can i do please help

 

[A-android-B]

Restore the back up you made when thou rooted

** these are just words **