Currently i'm stuck in act III, because i can't switch back to the first weapon which is needed to interact with some mechanism.

When i press the key to switch weapon it does nothing, remapping the key don't fix the problem.
I tried to use a controller instead but this don't work either.

I restarted the act multiples times. But i always have the same problem, when a retrieve the "gun" i am stuck with it, but the first weapon is needed later in the act.

I restarted on a new save, uninstalled and reinstalled the game, didn't fix the problem either.

It is a bug or am i missing smth in the level ?

Does someone have the same issue ?

Does someone have a fix ?

Keys 1,2,3,4 were not working because i don't have a qwerty layout, but mvt keys in my inventory worked fine, I just didn't realise it was a way to switch weapon thanks you for your response.

i also had a problem with changing weapons. keys 1,2,3,4 did not respond and could not be changed in the settings.
the solution in my case was to change the system keyboard language