We had a leak in our kitchen and we turned the main water supply off to fix it, afterwards we had very low water pressure in only the kitchen sink. So we turned off the supply valve to kitchen sink to see if when we turned it back on the pressure would return to normal. It did not and the water was kind of black when it returned. Is this normal. Is the water safe to drink?

The water should be safe as long as it returned to clear, and the low pressure is probably sediment clogging the strainer on the faucet, which you can remove.

When you shut down the main line and then open it up, the air bubbles and turbulence in the line generate settled silt. Clean out the faucet aerators and run the water for a few minutes. Should be OK. This happens to me every time I change the whole house filter.