Your sash windows have been freshly decorated and there is no longer room in the frame to travel lower down if you ve pulled the window forcefully it s now stuck firm.
Sash window weights stuck.
Windows old enough to have sash weights have probably seen a variety of painters of various skill.
For a window without access panels you also need to remove the window casing.
Pull one of the sash cords until the sash weight hits the pulley then lower the weight about 3 inches.
Tie the sash weights onto the new cords and drop them back inside the wall.
Sash cord snapped if your sash cord snapped and the sash has twisted in the frame becoming stuck firmly then you are in luck this is the easiest fix.
How to replace window sash weights accessing the weights.
Access the window sash cords.
Pry the old sash cords from the sides of the window sash.
Replace the access doors to conceal the sash weights.
Prying off the window trim may or may not give you access to the weights but you won t know.