Re: My Inbox has disappeared. How do I restore it?
Welcome to iMore and sorry you are having issues with your iPad.
When you say your inbox has gone, are you using the default mail client? If so, have you gone to Settings > Mail, Contacts and Calendars and made sure the email account is listed and that the mail slider is set to show mail?
If you sync an iPad to iTunes and iTunes is not set to sync music, it will remove music from your device.
Is your iPad a wifi model or is it wifi/cellular? If you are trying to connect to the internet over wifi and it is not working, obviously make sure that the wifi setting is toggled on. Maybe you could find a friend's wifi or a local free wifi hotspot, like Starbucks, and try it there to see if it connects.
If it doesn't, reboot your device by holding down the power button and home button until the Apple logo appears, then release.
If it's a wifi/cellular iPad and you are trying to connect over the cellular network, make sure you have the correct sim installed and the data plan is active. Check in the settings in any event and make sure Airplane mode is not enabled. If it is, turn it off. Make sure that the Cellular Data toggle is on in Settings > Cellular.
I can't think of anything else off the top of my head but if I do, I'll post back. In any event, we have some incredibly knowledgeable people here and if I've missed anything, I bet one of those folks will be along to add the info in.
Good luck getting it sorted.