Hi,
I think you have two problems.The key not going into the lock, in our area of western New York is usually stuck waffers or pins in the lock. Try some penetraing oil sprayed into the lock several times over a few days will some times free up locks. If not then a locksmith that will take the time to take the locks apart and clean them out.
The other problem of the locks not locking will be either disconcted linkages unhooked or frozen up at the latch. Again penetrating oil and time will most likely free them up.

Instead of a locksmith you can also by new locksets
for the door with a new key. then of course you will
have different keys for your doors and locks but everything
will work nicely.

I personally just think that something has slipped off
inside or come apart. I have probalems with the door
knobs not wanting to go up or down and once i hit them with
some WD40 they were perfect. I did, and would advise, soaking
them with some good lubricating oil or grease once you
get them working again.

Good luck!

cheers,

karl

--
66' 4-door 122s, 66' 2-door 122s (RIP), 67' 220, 77' 245 GT Grill, 78' 244, 87' 245, 88' 245 (RIP), 91' 245, 91' 940se ...and always looking for more!

I typed up a big response to this post last night but for some reason it was deleted when I hit the submit button.

I have been through the lock rebuilding myself and it is not too painful. I'd recommend taking a bundle of digital photos to remind yourself how it all goes back together.

The thing that stumped me is that a previous owner had tried to fit the lock back-plate from a RH door into the LH door lock. In the end I had to machine up a new one from aluminium. You won't find parts like this new so unless you have a parts car nearby you might need to get inventive to repair worn out locks.

Further to George's excellent advice, be aware that the trunk and door key are the same - at least I've never seen them keyed differently, but I suppose they could be based on previous repair activity.

Cheers,
--
Barry -- 1967 122S 'Betty'

They tend to get out of adjustment after 25 years or so.
Once you get the door panels off it will be fairly obvious how they work
and what needs adjusted as far as the linkages are concerned.
IPD sells a neat tool for undoing the snap rings that hold the inside door and
window handles on. Once you get them off the remainder of getting the panel off
is fairly straightforward. I'd suggest that when you get in there you have a
vacuum cleaner (or maybe a bunch of terry cloth rags, depending on how wet it is)
and a good flashlight.
While you are in there make sure that all dirt and trash is out of the bottom of
the door and that the drains are open. I once accumulated over a gallon of water in the passenger door of Li'l Red. Since it was a 2-door there was more
space for it. Water accumulation in there is one of the main causes of lower door
rust. The rubber lip seals work but are not perfect.
Once you get in there you can also get the lock out so you can take it to a
locksmith. Be sure you pick an OLD locksmith!
--
George Downs, Bartlesville, Heart of the USA!

My car was much the same when I bought it. The previous owner had made up a home baked alarm system because he couldn't find replacement parts for the locks.

The first thing to try is to get some graphite powder from a hardware store and squirt it into the keyhole, then work the key in and out a few times. The graphite will lubricate the lock and may be enough to loosen the pins inside the tumbler. This won't fix the inside plunger problem but might enable you to lock it by key.

I'm picking that you really just need to pull the locks to bits and work out what is wrong. Quite simple to dismantle - remove door and window winder handles (I used a jewellers screwdriver to remove omega clips but you can get a special clip removal tool from an auto accessory store). Then unscrew door lock plunger and screws holding on door pull and steel top panel. Now you can take off the door card - I'd recommend a putty knife to lever out the clips from the door without breaking the door card.

Now you can see the workings you might be able to figure out why it doesn't work. There are 4 philips screws (I think) that hold the latch into the back face of the door. With these undone and a bit of contortion inside the door panel you should be able to remove clips to get the latch mechanism out. The door handle and lock itself can be taken out without having to remove the window. Working out the problem is just a process of elimination. You should be able to see how it is supposed to work. Basically with the key locked, the outside push-button should not actuate the lever to open the door. I had to make up a new aluminium back plate for the lock to get mine working again. The previous owner had tried to use bits from a RH lock on a LH door. These parts are definitely handed. You might need to find a donor car to get some parts off. Apart from new tumblers and keys, I couldn't find any supplier of new latch parts when I was trying to fix mine.

The only non-obvious thing about removing the tumbler is that there is a pin that is often covered by dust and grot at the base of the (outside) push button. Clean around the base of the push button and you will find it. Drive it out with a nail and you will be able to withdraw the tumbler for cleaning and closer inspection.

In the end I was able to get both front doors and the tailgate working well off the same key. While I was at it I fitted an aftermarket central locking system which makes the car far more family friendly. I had to weld the actuator push rods onto the wires that come down from the inside locking plungers. Next thing is an alarm with a central locking output so I can unlock by remote.