How to recover email address used to register Samsung Galaxy Tab 2 (GT-P5100)

[balanga]

I rediscovered  an old Samsung Galaxy Tab 2 but am unable to use it is I've forgotten the email address I used to register the device originally. I've also forgotten about any PIN I might have used.

The device has memory and sim slots and I can send SMS's to the device if  I insert a sim, but am unable to read it.

Is there any way to gain access to the device? Can use some sort of program on a PC to boot into the tablet?

I don't want to do a hard reset because of some photos on the device.

Any help/pointers would be appreciated. 

[Obsydian]

I have an S6 Edge mobile with the same issue, sadly no way to bypass it, there are supposed tools online, but I don't think they work.