One way of fixing a lot of iPad 'unexplained' behaviour is to restart the iPad by completely switching it off, rather than simply putting it into standby.
Press *and hold* the Power switch until the slider control appears asking whether you want to switch the iPad off. Accept the offer and a small rotating white 'bezel' logo will appear on the iPad screen while the iPad is powering down. It takes four or five seconds to complete.
When the iPad screen has gone completely blank and the rotating bezel has disappeared, press *and hold* the power switch for a few seconds until a white Apple logo appears in the centre of the screen, indicating the start of the power up process. Note that, during the power up, the iPad automatic screen orientation doesn't work, so don't panic. Power up takes about ten seconds. About two thirds the way through, the iPad plays a 'jingle' and then, a few seconds later, the process is complete, the Home screen appears and everything is back to normal.
This restart process seems to 'cure' a lot of unexplained behaviour. Some Forum members have recommended doing this at least once a week as good practice - after all, it is simply completely turning the iPad off and on.
I have had similar problems to yours, with the iPad suddenly not being able to 'find' my printer and this 'restarting' has fixed the problem. Hope it works for you too.
Tim
Scotland