Is your lawn uneven, burnt out or just in poor condition?
If so, you have a couple options. First, you can aerate, dethatch, top dress with new soil (if needed) and then re-seed. This process can take time to get your lawn looking presentable again and can sometimes be just a band aid to an underlying problem.
The second option is to completely restore your lawn which is typically a more economical choice and will create a beautiful lawn faster that will last for many years.