Try starting the phone in "Safe Mode". The items may well still be on the phone, but not accessible due to something not so nice being downloaded to the phone. If you can get in via "Safe Mode" you should then be able to delete/uninstall whatever was installed. Remove any updates that came at that time as well.
To get into "Safe Mode" please do the following.
1. First turn off the phone.
2. Next press and hold "Power" until you see the manufacturers logo on the screen, then release the power button.
3. "Quickly" press "Volume Down" and hold it for few seconds until you see the message "Safe mode: ON" or something similar.
4. If you wanted disable it, simply repeat the steps above, and you should see "Safe Mode: OFF" rather than on.