Activation lock

The password for your Apple ID can be set back:

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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 your Apple ID, we can help you find it.

If you forget your password, you can reset it from your device or your Apple ID account page.

If you can't find your Apple ID or reset your password, you'll lose access to your account and might 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.

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copied from: Activation Lock for iPhone, iPad, and iPod touch - Apple Support

If you can show Apple Support the original purchase receipt, they might be able to disable the activation lock.

You can only call them, here is the page with all phone numbers:

Contact Apple for support and service - Apple Support

If needed, Apple Support will provide a mail address to mail the purchase receipt to them.

Neither we (just users like you) nor Apple can help you.

In order to bypass activation lock, you need to have the credentials that were used to activate that iPhone.

Without them, that device is useless to you.

If you're the original owner of that model 5, and you can prove it showing the receipt / invoice you got when you bought it, you can ask for help at an Apple Store.

Regards

Giulio

Activation lock is for iCloud locked devices. Do you trying to use your previously owned phone or is it used by somebody else? In the case if it’s locked to your iCloud, you can easily resets your password by getting an email or from answering security questions.