grace, try to remove the battery for a while, then reinsert it. If that does not help you may have to perform a hard reset. Performing a hard reset removes all data including the Google account, system data, app data, app settings, and downloaded apps. Only perform a hard reset if absolutely necessary. Pictures, videos and music are also removed.
- Ensure the device is powered down.
- Press and hold the volume down button then press the power button.
- Note When the 'Permanently Erase' screen appears, release the buttons.
- Press the Power button to perform the reset.
- Press the power button again to confirm.
- Note This boot process takes several moments, reference the progress bar located in the upper-right. If the device hangs or freezes, remove/replace the battery." from here. Hope this helps, good luck