how to restore iPhone 6 messaging ?

Try closing the app (double tap home button and swipe messages app upwards). Now try opening it again.

If it's still crashing, try restarting the phone (hold down sleep/wake button, slide power button to the right)

If that still does not work try updating to the new iOS if you have not done so already

If you have ever backed up your iPhone to iCloud or iTunes you should be able to restore your iPhone text messages from the backup. In fact unless you disabled the automatic sync option in iTunes, you should have created a backup everytime you synched with your PC or Mac. (See also: Create a group of contacts on your iPhone.)

Unfortunately, iCloud doesn't back up SMS in all territories, and for all phone operators. My UK O2-operated iPhone 5 falls into this category. So the following may not work (which is a shame because this is the best backup you can have for your SMS messages). You'll need only to go to step 2 to find out.

1. Login to https://icloud.com with your Apple ID and password

2. Click on Text Messages (if it isn't there your messages haven't been backed up).

3. If it is there searched the messages to find the ones you need.

4. Now go to your iPhone and choose Settings, iCloud on your iPhone.

5. Turn off Text Messages (or ensure it is turned off). I know this sounds counter intuitive but stay with it.

6. You'll see a pop-up. Select: 'Keep on My iPhone'.

7. Now turn back on text messages.

8. Tap 'Merge', and wait. After a few minutes the deleted text messages should appear back on your iPhone.

Also you can Retrieve Deleted Text Messages on iPhone 6.

Restore deleted tests on iPhone: from iTunes backup

Don't worry if the above didn't work. We have two further options to try. First let's try recovering deleted SMS messages via an iTunes backup. (See also: How to send group texts from Android and iPhone.)

1. Connect your iPhone to the PC with which you sync it. iTunes should open (if not, open it manually).

2. You should see your iPhone in a box, top righthand corner. Select it.

3. Now choose 'Restore backup'.

4. All the data you previously backed up will now replace the data on your phone. It will take a few minutes. As long as you haven't backed up subsequent to deleting those text messages, they should now appear on your phone handset.

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Restore from iCloud

If you have ever backed up your iPhone to iCloud or iTunes you should be able to restore your iPhone text messages from the backup.

Unfortunately, iCloud doesn't back up SMS in all territories, and for all phone operators. My iPhone on O2 falls into this category. So the following may not work. You'll need only to go to step 2 to find out.

Login to https://icloud.com with your Apple ID and password
2. Click on Text Messages (if it isn't there your messages haven't been backed up).
3. If it is there searched the messages to find the ones you need.
4. Now go to your iPhone and choose Settings, iCloud on your iPhone.
5. Turn off Text Messages (or ensure it is turned off). I know this sounds counter intuitive but stay with it.
6. You'll see a pop-up. Select: 'Keep on My iPhone'.
7. Now turn back on text messages.
8. Tap 'Merge', and wait. After a few minutes the deleted text messages should appear back on your iPhone.

Restore from iTunes

Unless you disabled the automatic sync option in iTunes, you should have created a backup everytime you synched with your PC or Mac.

1. Connect your iPhone to the PC with which you sync it. iTunes should open (if not, open it manually).
2. You should see your iPhone appear. Select it.
3. Now choose 'Restore backup'.
4. All the data you previously backed up will now replace the data on your phone. It will take a few minutes. As long as you haven't backed up subsequent to deleting those text messages, they should now appear on your phone handset.

Recover with third-party apps

If neither of the options above has worked, it is time to go nuclear. Well, not nuclear exactly but it may cost you a couple of quid, and there is no guarantee it will work.

We've never used either of these, but a couple of third-party apps appear to have a good online reputation. Because even after you have 'deleted' messages they remain on your handset until overwritten, you should be able to recover deleted messages using these utilities (and others).

Source: http://www.pcadvisor.co.uk/how-to/mobile-phone/restore-deleted-text-messages-on- iphone-365154/