The answer to 'sod turning brown' is that there are several common causes, including improper watering, disease, pests, or poor soil conditions. Symptoms include the grass turning yellow or brown, wilting, or thinning out. Solutions can range from adjusting your watering schedule, treating for disease or pests, or improving the soil through aerating, dethatching, or topdressing.
If the issue is due to improper watering or minor pest/disease problems, these are often DIY-friendly fixes. However, if the sod is extensively damaged or the root cause is unclear, it's best to call in a professional landscaper to diagnose and treat the problem properly.