Kitchen sink hot water pressure disappeared

I live in a 20-unit condo building, and unfortunately there's just one main water shutoff for the entire building (asides from individual valves at toilets, etc.) Recently someone was out doing work on our hot water heaters that required shutting off the water. After turning it back on, I lost most of the hot water (but not cold) in my kitchen sink. I assume this means that they turned the water back on and there's now debris in the hot water pipe leading up to the sink. I confirmed with my neighbor directly below that he does not have an issue. I assume he's on the same hot water pipe, so I'm guessing the partial blockage is between the two.

What's the fix here? It will definitely involve a call to the professionals, but would like to know more about the problem and solution.

Some faucets have filter screens on their supply hoses...it might be as simple as removing the supply hose and cleaning out the screen. Or, it could be in the faucet's cartridge. Sometimes you can remove it, clean stuff out, then replace. Sometimes it's internal to the cartridge, and you have to replace it.