You can use Find My Mobile to unlock the screen, if you set it up, otherwise you will have to rely on Google Back Up or One Drive depending on what you set up.
Just read that Samsung believes there's mother board damage. This is not good and possibly why Find My Mobile isn't working. Looks like your data is gone, in that case. If the data is important you will need to find someone that will access and recover the data from the chip. This is going to costs a few hundred pounds.