I have been trying the change the screws connecting the toilet tank, i managed to remove the tank but the nut it completely rusted and became one with the screw.
I tried holding the screw in place and rotating the nut to no luck. next i used WD-40 (sprayed it and left it for an hour then sprayed it again and left it for another hour with no luck).
I don't have access to a drill to drill out the screw top also i don't know if it may damage the porcelain which is the same reason i can't use a blow torch.
Is there a way to remove this without cutting it off ?
Update: I actually cannot drill the head off as to avoid any damage to the porcelain.
Update 2: Here are some images from the top-bottom view (sorry about things being dirty):