I cant open any app including settings
when I try to open any app it flash a full screen and won't open going back to app screen
iPad, iOS 8
Try a forced restart: Simultaneously hold down the Home and On buttons until the device shuts down. Ignore the off slider if it appears. Once shut down is complete, if it doesn't restart on it own, turn the device back on using the On button. In some cases it also helps to double click the Home button and close all apps BEFORE doing the restart.