The old phone, did it have an SD card that the photos could have been saved to? If so, I would check that card. In the old phone if possible.
Also, if the old phone was synced to a google account, and the photos were in the account instead of the phone, then you would only have access to them through that same account. If you used a new one on the new phone, that would be why you can't access them. If that is what happened, then you just need to download the photos to a computer from the account, then connect the new phone to the computer via USB cord and copy them over to the phone.
If none of the above is what occurred, then when you stopped using the old phone you may well have deleted things. They won't move over to a new device...