Why can't I type a password on my BB 8520?

i downloaded a theme on my bb 8520 and suddenly the phone requires me to restart it. after i restarted the phone. i cant type the password lock. what should i do? i tried to pull out the battery and put it back again. but nothing happens. it's still on the home and cant type my lock code.

if you can't delete the theme that is causing the issue, you are going to have to reload and OS to your phone, and lose all your data to get control back. I hope you have a backup already.