If the phone is stuck and it's not loading past the welcome screen then the solution is easy. All you need to do is to perform a hard reset of the phone in case something got broken and made it unusable.
In order to reset the phone to its factory defaults, please turn off the phone first then use the following button combination: Volume Up + Send Button. Keep these buttons pressed until you access the recovery menu. From that point choose Wipe Data/Factory Defaults and activate the option. Then reboot your phone and it will work as it should.