Phone keeps rebooting when I enter the password.

Everytime I power the phone on and enter the password it just reboots all over again. I cannot access any apps on the phone. Also an error message pops up and says. (Unfortunately stock Android has stopped working). Can someone please help me. I cleared the cache partitions by holding volume up and power button but that had not helped. I really do not want to factory reset the phone. Please someone help me.