Hot water is not getting hot in kitchen sink only
It depends on how you get hot water. There may be a "tankless" water heater under the sink, or very close to it, that was turned off during countertop installation. This is likely, because the sink is getting water, but it does not get hot. If that's the case, just find the instructions for turning it on, and check circuit-breakers as well.

These heaters are popular where energy is costly, since they run only on demand.