There could be a pension or widow's pension. It would be in the state archives where he or she resided. It is also common for a soldier to move to another state. He would file in the state where he was living. My GGF joined in Texas, never returned. He then lived in Mississippi, Tennessee, Mississippi and Florida. He filed for pension in Florida and died the day before it was approved. But, I now know much more about him. The pension led me to Texas, Tennessee and back to Florida. While looking for him I collected so much material, I opened a web site about his brigade.

You need to find where he lived. You may know where he is buried. Start looking for pension request in that county. The county judges usually approved pensions. Some counties still have those records. Others are held at State level.