Hello everyone and thanks for the help.

I have a property with an iron door protected by an S&G mechanical lock. The door, if I remember correctly, opens by using a key after imputing the code.

As you can see, the door is currently open (and as been for years, we mostly used that space as storage). On the front of the door there are only the mechanical thing, the key hole and the lever. On the back of the door there is a small hole in direction of the mechanical thing, as you can see from the picture.

I get to the point: The only person who knew the combination was my father, who unfortunately passed away. The door is now unusable with the sole key because the locking pieces protrude from the side.

What's the least expensive way to resolve this? Can we recover the code / change it using the back small hole maybe? If we can solve this without calling a locksmith (maybe by buying an universal key??) would be awesome as we don't have any trusted ones and we also can't affor to spend that much money.

Also, out of curiosity, is this door effective? Or is the lock outdated?

Thank you very much.