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There isn't really any reason to suspect that there was connection between the horn pad repair and the symptoms you are experiencing if the repair was approached normally.
I would be concerned that perhaps they attempted to do some sort of "other" repair inside the dash to try to circumvent the horn issue initially leading to issues.
Regardless, the only thing that really could have occurred here to result in window loss, dash lighting, and indicators would be a fuse failure. I would want to go over all of the fuses both under bonet and in dash and make sure something did not pop. It is very likely you have a blown fuse here is all, and hopefully from something momentary and not any sort of hard short they may have created.
If nothing is found with the fuses, then I would strongly recommend getting it back to the shop that did the repairs as of course it is highly unlikely to have three completely unrelated failures to just happen to crop up at the same time... it is more likely a result of something they did and being that it would have to be some sort of modification (if no fuse is at fault), there is no real textbook to go by to determine what exactly happened since we have no idea of what all they did while they were in there.
There are no single modules that would be relative to all of the issues you have failing at once.
Specifically... the turn signals operate through a flasher module under the dash, but it has no effect on the windows or instruments operating. The window module is built in to the master window switch and has no effect on the others. The sunroof module is built into the motor as well. The instruments are all standalone in each behavior (speedo/tach vs temp vs fuel vs warning lights, all handled separately).
Given the broad range of malfunctions you have, for them all to be inter-related you are pretty much down to a anomaly in the dash (something unplugged or loose from when they were working on it) or multiple fuses popped (none of the areas you are having problems with share any fuses).
With regard to the 4WD operation, a scan of the system to see what transfer ecu/TCM faults (not OBD faults) are present to prevent operation.... but again given the assortment of problems after the work performed, I would want to get the other issues sorted before assuming there is an additional issue. If the 4WD worked before, it is likely going to be in the same situation with the other issues, a result of something left loose etc.