i have a iphone 7 and it has activation lock on it but i haven’t used it in over 4 years, i have a new gmail but it won’t let me put a new anything

With regards to Activation Lock on iOS Apple notes the following:

If you forget your Apple ID or password

• Your Apple ID is the account that you use to sign in to all Apple services. Usually, your Apple ID is your email address. If you forget it, we can help you find your Apple ID.
• If you forget your password, find out how to reset your Apple ID password. 

If you can’t find your Apple ID or reset your password, you'll lose access to your account and may be unable to use or reactivate your device. To help prevent this, visit your Apple ID account page periodically to review and update your account information.

Activation Lock for iPhone, iPad and iPod touch – Apple Support (AU)

You can try to contact Apple Support regarding the Activation locked device under the circumstances, however it is extremely unlikely that they will be able to unlock the device. I have heard in specific circumstances and with proof that you own the device and that the account it is locked to matches your ID apple may be able to unlock it but I cannot stress enough that this is again EXTREMELY UNLIKELY.

To contact Apple Support follow this link Contact — Official Apple Support (AU)