I bought this iPhone from somebody and it’s locked he said he didn’t know but I have proof that I bought

If you want to contact Apple support to discuss your problem, see the support options below. Alternatively, if an Apple Store is open in your area, then you can go there to deal with your problem. In this case, you can make a genius-bar appointment (https://www.apple.com/retail/geniusbar/) if you want.

Get a call from Apple support to help solve your problem using this

link https://getsupport.apple.com/?caller=kbase&PGF=PGF63005&category_id=SC0245&symptom_id=23362

Apple ID Support https://support.apple.com/apple-id

Apple ID account security for country-specific and

region-specific help https://support.apple.com/en-us/HT204169

Get Support: We’re here to help https://getsupport.apple.com/. Go through the options to find the best support option.

you will need to contact the previous owner to have them log out of iCloud or go to https://www.icloud.com/find/ My Phone and erase the device, then remove it from their account. If you can’t do that, the device is useless. Apple won't unlock it.

Turn off Activation Lock - Apple Support.     

You acquired your device second hand from someone other than Apple or an authorized Apple reseller. The information below explain what has happened. You apparently didn't know to heed the advice given below.

"Before you buy/acquire an iPhone, iPad, or iPod touch from someone other than Apple or an authorized Apple reseller, make sure that the device is erased and no longer linked to the previous owner’s account."

And see: Activation Lock for iPhone, iPad, and iPod touch https://support.apple.com/en-us/HT201365. See this heading Check for Activation Lock before you buy/acquire a device from someone else.

 What all this means is that there is no way we can help you. We are not authorized to remove the activation lock from any device. And, under your circumstances, Apple support will not help you since you cannot provide proof of ownership that they will consider to be sufficient. You would need and have your purchase receipt for the device from an authorized Apple seller with the device's serial number on it. You can't have this information under the circumstances you describe.

All I can suggest is that you try to recovery the needed password (or possibly the purchase price) from the party you acquired the iPhone from. Recovering the password is the only way the phone can be made functional for your use. And getting it from the person you acquired it from is the only way to so. 

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you will need to contact the previous owner to have them log out of iCloud or go to https://www.icloud.com/find/My Phone and erase the device, then remove it from their account. If you can’t do that, the device is useless. Apple won't unlock it.

You know what I have already said twice. It is natural you have the phone's serial number since you have the phone. But, really, the photo proves at most that you have, or may have had, the phone at some time.

It doesn't matter that you "bought it", or have a receipt showing you paid for it.

The problem here is there's a near 100% certainty you bought a stolen phone. This means you were scammed. We see these here daily. A stolen iPhone still legally belongs to the person it was stolen from (or possibly lost). Either way, you now have a useless device.

Apple will not help you unlock someone else's phone. That would be aiding and abetting.

You have only one option. Return the phone for a refund. If you cannot do that, then sorry, but you've lost your money.

Only in the very unlikely event they could track down the seller.

If you bought it online (and there are LOTS of stolen phones sold through eBay), then it will be very difficult.

If locally, and you can meet with this person again, try to get your money back. But be aware, people have been injured, and sometimes even killed trying to confront the criminal. If the seller does agree to meet again, I'm make darn sure I had a police officer with me.

As I said, "you would need and have your purchase receipt for the device from an authorized Apple seller with the device's serial number on it.