tried to start the car but it won't start. I observe the brake is hard and gear can shift without using brake

 

Brake pedal is hard because all the vacuum in the booster has been used up. Maybe you stepped on the pedal a couple of times in frustration when the car did not start.

How does the car not start? Key won't turn all the way? Key turns to start position, no noise from starter and key springs back to the on position with warning lights on dash?

"gear can shift without using brake" - You can move the shifter from park to any other position and back without the key on or your foot on the brake?

 

Yes I can move the shifter to any position without the key and without my foot on the brake .
what might be the cause

The key turns to start position and starter makes noise but no ignition

How do I get the vacuum back please

 

You are in NG - what engine do you have? 5, 6, 8, cyl gas or 5 cyl diesel? The 6 and 8 use longer lasting chains.

Vacuum is created with an electric vacuum pump on the 5 and 8 cyl gas, and comes on with the ignition. You can hear the pump under the hood with the key on. (unless it's bad) A mechanical pump is used on the 6 cyl gas and the diesel. On those the engine has to run for the pump to develop vacuum.

If your starter is spinning the engine over - but the engine is not catching, and you have no vacuum, so you either have the 6 cyl gas or diesel - with the diesel the timing belt can come off/break and prevent the engine from starting. How many miles on the car? Only the 5 cyl gas or diesels have timing belts. The 6 and 8 use longer lasting chains.

 

Engine is 6cly and mileage is 159000

 

And it's gas type with chain

 

So the 6cyl gas engine with a mechanical vacuum pump. Do you have fuel pressure? Do you have spark? Are there any codes stored? Those would be some logical next steps.

 

Ok I run through to confirm fuel pressure , codes n sparksThanks