Hello,
Just the other day I lost all the Hot Water pressure in my house. Water comes out but very little and it takes a while before it gets hot. The cold water is fine and we have recently installed a new water heater. Any ideas what I should do?

Your installation was faulty. If you paid someone to install the tank call them back. Check that the supply valve is fully opened as well as any valve on the hot water exit side. You lack pressure coming into the tank or volume coming out of the tank.

On some models they come with short threaded pipes for the top of the water heater. Some have a rubber flap, some have a ball. The ones with the ball are color coded and directional. Make sure the direction is correct. Oh, and make sure the valves are fully open.