Please note that we've updated the Mount & Blade II: Bannerlord save file system which requires you to take certain steps in order for your save files to be compatible with e1.7.1 and any later updates. You can find the instructions here.
Can you try to verify the game files through Steam after deleting all of the contents of "C:\Program Files (x86)\Steam\steamapps\common\Mount & Blade II Bannerlord\bin" folder and try launching again?
You can also check if this folder has any .dll files that are not from our side. It should look like this, please remove any .dll files that is not listed below: