Why does it keep saying the process com.android.phone has stopped?

It appears that your android system is corrupted, it might be the cause of a recently install app or a software download that went bad. If the phone allows you try to safe your personal data that´s saved on the phone, because the process you need to do will erase all the personal data and the accounts on your phone, however, the data that is saved on your MicroSD wont be affected.

Now:

1. you need to power off your phone and charge it to 100%

2. Press simultaneously Volume Up Key + Power Key and hold until you see the recovery menu (or the android icon that means that recovery is loading)

3. Move the highlight with the Volume key and go to Wipe Data/Factory Reset, Press Power Key

4. Then, go to yes and press Power Key

5. Then, when the process finish, go to Reboot

6. Your phone will be Factory Restored and the error shouldn't appear again