Hi @KidLight 

Internally, normally it's the blue and red wires which should be connected to points a and b.

Then the cover is placed on the back part and secured by the center screw.

This is not an official ISRA wall socket.
This is a typical old phone wall outlet which u need a 4 pin phone connector with.
It can also be used to install ur xDSL modem.  
You're missing a screw which will go into the middle hole to hold it all down.

Yeap, using it with a four pin phone connector to my modem. Im trying to piece it back together but it doesnt want to fit together properly for some reason. I noticed that one of the meta bars isnt closed like the others, is this something that might explain why it isnt fitting properly with the outside case?

I circled it to make it clearer here:

 

A different angle:

 

The circled one looks fine on the other hand the mirrored on ( the one on the left ) looks bend.

The bottom left is the one that's looking odd. The end should not be folded together.

Both bottom points have no function for the xDSL signal to your modem.
As mentioned before it's only the blue and red wire on the two top points.

From what I can see all pins, especially the one below on the left, appear to be bent or broken. KPN at 0800-0402 can repair this at your cost.

Or get this:

https://www.gamma.nl/assortiment/q-link-telefoon-contactdoos-opbouw-modulair-4-polig-wit/p/B547149#:~:text=De%20opbouwcontactdoos%20is%20bedoeld%20voor,geschikt%20voor%20gebruik%20in%20Nederland.
 

And repair it yourself.

Thanks!

This wire (the silver one with the arrow pointing at it) seems to have come loose. Do I need to reattach this to the circled screw?

 

Ah thanks for the info. Might fix it still just to ensure that there isn't any risks from wire damage, if anything (It's my first time doing something like this so I'm really a noob with what the right steps are)

 

Will try to fix this today, and if I can't, will buy the extra part and call KPN to have someone fix it for me :)

Do you have any tips to know before I try to fix it myself? (eg: protective gear so I dont get electrocuted haha)

Do you also know how much it might cost if KPN comes to do it, and what exactly this part is called since I cant find it online?

Tho it even is bend it still works cause the pins only need to make contact with the strip.

The gray wire is ur earth u can reattached that or just cut it off.
There little to no voltage on these wires u can touch them with ur bare hands.

So I tried taking out the two screws for the bottom half because the outer case wouldnt fit in it since one of them was bent. 

After taking it out, the outer case fit back in but still doesnt work for some reason.

This is what I mean:

 

Hoping its a problem with this because the connector also fell apart when I dropped it, heres what it looked like before I put the adapter back together:
 

Should I have kept the two screws I took out in?

Okay, so I fidgetted with the bottom two screws for a bit to make them fit into the case and it ended up working! 

I left the silver cable (the ground one) unconnected to the bottom left screw though. Is this something I shouldnt have done? Dont want to short circuit my things or even worse start an electrical fire because of this haha

Ended up putting the ground in just for the added safety

 

Thanks for all the help anyone! Lemme know if anything looks weird :)

Good to hear you have solved your problem. Glad I could help.

No risk of that. Low voltage & low power.