PvZ 2 keeps crashing

Could you give us more details about your gaming device?  the make and model number, the amount of free memory and if you turn off internet data (No WiFI and Flight Mode on) would you be able to get pass the purple 'Play' button and getting into the game?

My device is an iPad mini 2, and the number is ME279LL/A, and there's about 5 to 6 gigabytes of free space left. Also, the game still crashes when I turn off Wi-fi and turn on Airplane mode.

It sound like the data corruption is local to your device since you cannot access the game even without internet data. 

Before you attempt any further 'fixing' I would suggest to make sure you screenshot or note down your player ID to be on the safe side.

On IOS the player ID can be found  by either clicking spanner icon in the game's main menu or in the IOS system, under  Settings > PvZ 2 > PLAYER INFO

Things you can try are:

1. If you have not register your email with EA to get 100 free gems yet and the spanner icon is available and can be accessed, it might worth it to register now as this would associate your PVZ2 account with your email.  Once this is done, if you have a phone (it does not matter whether it is an Android or IOS device, as the email association works on both platforms) you can try to install the game on it and do the email register with the same email address, it will then give you an option to recover your game saved progress on the phone.

2. Once you have the your account recovered, you can then delete the game on the iPad and try to re-install it again and see if the problem is cleared.

3.  If there is no spanner icon (because you have NOT entered your age as an adult) as mentioned on step 1 or it is there but it cannot be accessed, please exit the game, log in to Game Center and then restart the game, hopefully this action should have saved a copy of your game progress with Game Center (just hope it is not a corrupted one).  You can then try delete and re-install the game to see if the problem goes away.

4.  If none of the above works, your last resort is to contact  the Help Center (by clicking the link at the bottom of this page and fill in the Missing Content form, you will need to provide them with your player ID and report that you cannot access your game.  An Advisor should be able to help you to recover your account but this is time consuming and patient testing.  Sometimes it might take a few days and possibly more than half dozen of emails back and forth, but please be persistent.

Good luck.

Thank you for the help. However, I haven't signed into Game Center until I reached Lost City in PvZ 2. Does it save that progress there?

Yes, the Game Center would have saved a copy of your latest progress. 

Let's say if you have completed 3 worlds out of 12 last week. and you completed a further 5 worlds during this week then signed into to the Game Center at the end of this week, the Game Center should have saved your latest progress which is with 8  worlds completed.