Start with reset of the iPad, but close all apps fIrst.
In order to close apps, you have to drag the app up from the multitasking display. Double tap the home button and you will see apps lined up going left to right across the screen. Swipe to get to the app that you want to close and then swipe "up" on the app preview thumbnail to close it.
Hold down on the sleep and home buttons at the same time for about 10-15 seconds until the Apple logo appears on the screen after which time you can release the buttons and let the iPad start up.
If you are running less than iOS 7, you close apps from the recents tray at the bottom of the iPad when you double tap the home button, It helps if you provide a ititle more information about the device when you are seeking help.