I put Tails on a usb drive. Booted it up. Put a persistant volume on a second dive. Rebooted and now all i get is ' no bootable disk. Insert and press button'. Tried f1 f2 f12 and just repeats itself.
Most probably by "Put a persistant volume on a second dive" you damaged / repartitioned your boot drive.
Boot your Tails, and post the output of "sudo fdisk -l"