You've had your iPad or iPhone for a while and it has gotten to a point where the computer no longer recognizes the device. It was just working yesterday, but it seems to have taken a turn for the worst. Is the device dead? Not quite, but it may need some care, and worst-case scenario it may need to be sent in for iPad or iPhone repair.
Apple's support website said symptoms of iTunes or a computer not recognizing a device means that the gadget doesn't pop up on the screen when plugged in. Either the device said it cannot be restored in iTunes, there's an exclamation point, question mark, plug symbol or “X” next to the device in Device Manager or the device just flat out may not be recognized by iTunes anymore.
People can look at Apple's support website for some general advice on what to do to help fix their device or get it back to normal, but some solutions may require more than just restoring the device back to factory settings.
Sending the device in for repair can help revitalize the device back to like-new conditions. Not connecting could simply mean the USB plug broke and needed to be fixed or replaced. But until you look into it, you will never know if the device can be fixed, and it is certainly a lot better to get a free repair estimate than immediately drop hundreds of dollars on a new iPhone or iPad.