Once in a while, it happens to all of us. A stubborn window or door will refuse to let itself opened. The reasons are many: it’s either a rusty lock, an old opening system or they are simply jammed. Usually, it’s risky to attempt to open them using force because this might damage them. So how do we deal with stuck windows and doors?
If the door is stuck at the bottom, scraping on a threshold, there can be a number of reasons: the door is both loose, in which case you should check the screws and hinges, or it may have swollen due to humidity, and in this case you should wait for the drier season and check it again. Another reason could be the settling of the building, if you live in an old one. This can modify the door alignment and put pressure on it. If that’s the problem you can either replace the door, or take the old one out and plane the bottom edge. 

If the windows sashes are jammed, this can happen if they are not opened often or if they have had many coats of paint. Paint gets sticky and the windows don’t slide easily. Unsticking sash windows can be tricky. You need special tools and take special care in how you handle them so that you don’t break the glass. You can use a thin blade to remove the paint between the frame and sash, but you may have to put some pressure on the window and use a hammer. This can be a job that is best left to a professional, or else you may find yourself in the position of needing to buy new windows. If you have manage to open the sash window, move the window up and down a few times so it starts to move easily again. Remove the paint coat from the channels and use a sandpaper to smooth the edges. 

Old windows can get stuck very easily and this happens because they have been designed with one-way security screws so that they won’t come out. What you need to do is to get rid of those screws, remove the old lock and replace it with a new one. 
If the key lock is stiff and the keys don’t turn, you just have to add a little graphite powder onto it and put in the key. Pull it out and put it back in a few times, without turning it. After this, you can turn it a few times and the door will open. If this doesn’t work, change the lock.