Ignoring the sarky comment and link below, (which I haven't clicked on and might possibly give the same answer as me).. I feel that this site is a forum for repair experts to give direct advice based on experience rather than point you in the direction of a youtube link..
Your problem may be caused by a sticky locking mechanism, which can sometimes be resolved by giving the front of the washing machine a good old fashioned thump with your hand in the area directly right of the door handle whilst trying to open the door with the handle. This can sometimes free up the mechanism and allow the door to be opened. If this works, I'd recommend replacing the lock mecanism before you use the machine again.
Rupert, May 2020
