Hi bigant. What was the last thing that you did before that happened? In any case, a hard reset may help in that situation. But be warned; Performing a hard reset removes ALL data including the Google account, system data, app data, app settings and downloaded apps. Only perform this reset if absolutely necessary.
Also, pictures, videos and music are also removed. It's recommended to backup this data.
To do a hard reset, simply follow these steps:
1. Press and hold the Power button+Volume up key simultaneously until the 'hard reset menu' screen appears then release.
2. Press the Power button to confirm.
3. You will be asked "Are you sure you want to continue with erase?" Press the power button to confirm.