Is there someways to retrieve my messages in gmail that were automatically deleted. Also any way to prevent this from happening

Go to Settings > Mail > Accounts > Tap your Google account > Do you see Mail Days to Sync (not all accounts have that), but if you do, change the setting there. You should, by the way, still be able to see the messages there.

There is no time limit in the iPhone settings, but there might be in your gmail settings. On your computer go to https://mail.google.com and check the settings there.