A hard reset will correct many Chromebook issue.
To perform a hard reset on a Chromebook, press refresh and power at the same time.
If a hard reset does not work, you may also try a policy refresh.
- Launch the Chrome browser and go to "chrome://policy"
- Click "Reload Policies"
- Wait 60 seconds
- Restart the Chromebook
- You may have to repeat this process a couple of times