Hi wisetkg,
Ensure that you know your Gmail email and password by trying to sign in at Gmail.com. After confirming that, remove the Gmail account from your iPhone and add it back again. This forces a resync with Gmail to your iPhone that should in turn restore your connective sync to other devices.
"In the Mail app on iPhone, you can add email accounts to send and receive emails, and remove email accounts you no longer need.
Add email accounts
The first time you open the Mail app on your iPhone, you may be asked to set up an email account—just follow the onscreen instructions.
To add additional email accounts, do the following:
- Go to Settings
> Mail > Accounts > Add Account. - Do one of the following:
- Tap an email service—for example, iCloud or Microsoft Exchange—then enter your email account information.
- Tap Other, tap Add Mail Account, then enter your email account information.
Log out of or remove email accounts
- Go to Settings
> Mail > Accounts. - Tap the email account you want to remove, then do one of the following:
- If you’re removing an iCloud email account: Tap iCloud, tap iCloud Mail, then turn off “Use on this iPhone.”
- If you’re removing another email account: Turn off Mail.
- Note: To remove the email account from all apps on your iPhone, tap Delete Account."
Cheers!