Re: Windows nailed and painted shut, every latch stuck
If the nail has a head, you need a block of wood and a curved-claw hammer or a small crowbar. If it's a finish nail, then some vice-grips and a block of wood. The block is necessary so you can maximize the leverage.
The windows can be infinitely improved by disassembling, stripping the paint everywhere, removing the glass, painting with oil, reglazing, and retrofitting with weatherstripping, which can be high-dollar interlocking metal or dime-store self-adhesive v-plastic stuff.
Remove not the ancient landmark, which your fathers have set.