CDL only locks the front and back driveshafts in sync. The 123 selections only work in the low range with M selection on.

This sounds more like an electronics issue (which, unfortunately, I can't say much about) rather than a busted trans.

This might be totally useless advice, but try disconnecting the battery, wait for 20 min for the residual charge to drain down connect back again, and see if something gets unstuck.
If you have a few bucks to spare, I'd purchase an icarsoft scanner - it can read the trans codes.

 

As for transmission electronic issues, most seem to be low voltage problems. Check your battery voltage, and alternator voltage. If you are much less than 12.5v, this could be your issue.
The next most common problem (or maybe the first) is incorrectly servicing the transmission fluid. Make sure you’ve done it by the book. The engine needs to be running when you check the level, after cycling through all the gears.
You said the front drive shaft broke. It commonly damages the transmission when it flails around. Possibly the transmission survived, but some wires to it were compromised?

 

I know that I filled it properly I followed the YouTube videos to a t. My battery is the most expensive Walmart battery was was just replaced 6 months ago and I just replaced the alternator a week ago I just don’t understand if the front driveshaft was to compromise any wires why did 2 weeks prior to me getting this issue she drove just fine

 

Usually "driveshaft failure" would mean that it came apart and was flailing around banging into stuff. It sounds like you only had worn-out bearings on the u-joint (or at least it stayed in one piece). The expensive battery can lose charge if not recharged just as any other one (especially if it's been sitting idle for some time), so checking voltage is a good idea. I'd also def give it a try with disconnecting the battery.

 

I was driving it when it snapped back in 2021 I immediately stopped. The Ujoints completely snapped off so it had stayed bolted on both sides but the long side hung downwards and the broken part stayed straight where it was bolted. I’ve replaced the alternator, and the battery 6 months ago I charged it for 24 hours to see if that helped it had not, I might swap it out with another battery that I just got like 2 months ago for my suburban, same size and everything. Also my service engine light is not on

 

Youtube videos on how to fill the transmission don't necessarily show you how to do it right.
Was the engine running when you checked the fill level?

 

yes it was on when I checked and filled

 

So it sounds like it actually was flying around. I'd check for any dents and cracks on the case.

 

no cracks or dents on it

 

Hmm, next thing i'd probably do is to get the tcase in low, switch on the M mode unplug the transmission harness plug and switch the gears and check if you are getting voltage on the pins corresponding to solenoids. This will require getting all four wheels off the ground. If you are getting current on the pins then test the resistance on solenoids (by measurnig across pins in the socket), if that is ok then i'd proceed with test in my previous post.