Pull all the drawers out, and you should be able to access the lock bar. It’s generally at the back of the desk, and runs up through slots in all the drawers. It moves up and down with a small lever, which has probably become loose or bent.
At the risk of being, like, really obvious, have you tried searching for a video? Maybe using the manufacturer’s name, if you know it? There are videos out there about everything!
I searched YouTube. Desk repair finds refinish tips.
Search on desk locking mechanism finds a few vids on the lock. But nothing on adjusting the bar system.
I called a locksmith. They suggested calling a office furniture store. That’s my next step.
I look at removing the center drawer myself for a DIY repair. I don’t see a way. I sure don’t want to get it out and then can’t get it reinstalled.
These repairs are so simple at work. One call to physical plant gets it repaired. Physical plant has a couple guys that are pretty good with general repairs.
Last resort, I’ll talk to them and see if they want to earn some after hours $$.