If you are not dealing with physical damage to your Chromebook we ask that you first reset it. Please follow these instructions to about 1:34 of the video to reset and see if that fixes your issues.
At the login screen
Press Ctrl+Shift+Alt+R
click the powerwash button
wait for the reset to finish [may get the powerwash option twice], the device should auto reboot back to the welcome screen when done. Reconnect to wifi.
If you have an older device you may to follow the old reset procedure:-
If this does not resolve your issue please fill out our Chromebook problem form