Device registered to an old account that isn't active

Either recover use of the account or ask Apple to rest the device.

This Apple article has instructions for what to do if you have forgotten your Apple account password, or the system does not recognize the one you remember —> If you forgot your Apple Account password - Apple Support or go directly to this link —> http://iforgot.apple.com/

If you don't receive your verification or reset email, read this Apple Support article: If you didn’t receive your Apple Account verification or password reset email - Apple Support

"When you make certain updates to your Apple ID, we’ll send you an email to help you complete the update. For example, you might have reset your password, reset your security questions, or added a new email address to your account." Also check your junk mail.

If you find you can’t sign in, reset your password, or receive verification codes, you can request account recovery (read this support article: How to use account recovery when you can’t reset your Apple Account password - Apple Support ) to regain access to your account. Account recovery might take a few days or longer, depending on the specific account information you can provide to verify your identity. This is a multi-step process. More detail in —> Activation Lockout Issues - Apple Community and My Apple ID is locked, how do I fix it? - Apple Community

Apple can completely reset a device if a person can provide sufficient evidence of valid ownership. Read the requirements and steps for an Activation Lock support request at: https://al-support.apple.com/#/additional-support and links at the bottom right for the type of service requested. Apple says they may require "proof of purchase documentation” and that you need “proof of ownership documentation”, but does not detail what currently constitutes proof other than it “must include the product serial number, IMEI or MEID.” User reports on this community indicate that typically Apple will ONLY accept an original receipt issued by Apple or an Apple Authorized Reseller. Presumably this is the only kind Apple can authenticate against fraud since Apple is not involved in third party sales. Apple recommends that you "Keep your receipt after you buy an Apple device" --> Keep your receipt after you buy an Apple device - Apple Support

If Apple resets the device this will give you access to the device but won't restore access to the account used to lock it. There is nothing that can be done to expedite an Activation Lock request.

You don't have to "come up with the old password", you have to get Apple to reset the password. If you find you cannot prove account ownership then thank the hacking community for making it necessary to place so many requirements to getting access to the old account. Unfortunately this isn't like the old BBS days of the 1980s where the only consequences to somebody illicit getting access to an account was them posting under your name. Now it can literally mean they have access to all your private information and your bank accounts.

Likewise thank all the thieves out there who steal Apple equipment, with the result that Apple's customers prompted Apple to develop ways of handling the situations. It unfortunately works both ways though.

5 years ago you could have taken it to an Apple Store and depending upon the mood of the manager they may have reset the device for you. It was not an official service and a manager could just say no if they wished to. Then Apple made it an official service, but at the same time moved it online and set very strict requirements for removing the lock. You are welcome to take it to a store but I doubt they can do that for you now. I get hte impression it is no longer up to the store manager.

I did not suggest you hack your account. You would find that to be essentially impossible anyway. I was saying that if you are having problems resetting your password (by the way, even Apple does not know your password except in an encrypted format, so they couldn't tell you what it is even if they wanted to—all they can do is remove it) then the reason could be because of hackers, in response to whom Apple (and other companies) have been required to implement more stringent identity proof requirements before they will let you have access to an account.

As for hacking the hardware, ignore anything on the Internet saying you can do that. Even the FBI wasn't able to.