driver side window wont go up or down sometimes.but if you push down on the glass then it will go?
When you push on the window and the window works there could be two possible problems, the first could be the window regulator is sticking and when you push on the window it frees the regulator.
If you don't have to push hard on the window for it to work then I would think the window motor could possibly be bad. The brushes inside the motor could be sticking or worn where they don't make contact with the armature inside the motor. Moving the window makes the bushes make contact inside the motor and make the motor work.
Taking the door panel off and checking the voltages at the plug of the window motor can confirm this, if you have voltage to the motor and it won't work then it will probably be a motor related problem.
In the future when you ask for assistance we need more information like the year, model, engine size, manufacturer and any other information that can help me help you better.
Might want to lubricate the rubber window channel before pulling the door panel. Spray silicone down into the channel, front and rear of the glass, and see if that makes a difference.