Today's tip was inspired by an acquaintance who asked for help in buying a new iPad. Knowing that they had a fourth-generation iPad -- not far removed from the current iPad Air 2, I asked why. "Doesn't work anymore," they grumbled resentfully. "Lots of crashes, some apps don't even launch now." I asked if it had ever been turned off. "Every night," they said. I said, "no, not put to sleep -- turned off." "You can do that?!" they exclaimed.
You may laugh but you’d be shocked how often I run across people who have never, ever, years since they got their iOS device, restarted it or powered it down. Ever. It's a real testament to how solid iOS is, but no OS is impervious to faults, particularly with a long uptime and limited RAM as the iPad has.
If you haven't done it in a while yourself, do it now: turn off your iPhone, iPod touch, or iPad. You just press and hold the sleep/wake button for a few seconds, and a red slider bar will appear which you can then slide. Depending on how full your device is and how long ago you last did this, you may get a faint "busy circle" symbol for a few moments on a black screen before the unit goes entirely black, indicating that it is finally off.
Once that's happened, you can turn it back on in the same way: you'll see an Apple logo to assure you that you've turned it on, and shortly the familiar login screen will appear. For those in a big hurry, there is a faster method: press and hold both the home and sleep/wake button for a few seconds. This will trigger an immediate reboot.
How often should you do this? As preventative maintenance, I'll say once every few months, let's say quarterly. On the equinoxes, if you like. It's up to you, but don't wait too long. If your iOS apps start crashing, a restart is the first and primary step you as a user can take, and the good news is it works 90-plus percent of the time.
If this doesn’t help the next “fix” is to restore the device to factory settings - so BACK IT UP to iTunes on your computer. Restore sets the device back to factory settings and DELETES all your stuff: video, pictures, game scores ….