If the grass is actually dead and not just dormant such as what happens in the fall and winter then the dead grass may be hard to get to come back to life but sometimes it might.
In the fall and winter grass goes dormant and looks dead and brown in most areas and then in spring and summer months the grass comes back to life and gets greener.
If you don't get much rain then you need to water your grass to help it grow and thrive.
If the grass is completely dead and not able to be revived then you'll need to aerate your lawn and then put new grass seed down in the spring to get your lawn green again.
If you have some small patches of dead grass then you can put new grass seed in those areas after turning over the soil.
Then water the grass seed and after a month or so the grass should come back to green in those areas.