3 years ago had a large shed installed into our garden. We have decided to reposition to a new part of the garden but are having trouble dismantling the shed and removing screws. Almost without exeption, every screw has been driven too far into the wood making them hard to find and not only that the heads of the screws are knackerd to the point that a drill bit will not bite at all. My question, how do i remove screws? Thankyou in advance.