Need more info. Your question is sort of like asking "I have a car, what is it and what's it worth?"
There are numerous S&W models in 38 caliber. The serial sometimes has letters in it. Don't neglect to mention them if present.
First, look for a model number under the cylinder crane. It will appear as "MOD 19-3" or similar. If not present then the gun likely dates before 1957.
Here's the model number. This one is a MOD 25-2. Note the serial is also present but it's not always in this location. The second photo shows the butt where the serial is usually found.
Give a full (FULL) description. Fixed sights or adjustable?
Is the ejector rod under the barrel covered (shrouded) or is it exposed and visible?
A full and proper description along with the correct serial will enable someone to positively ID your S&W revolver. Photos are always helpful but they must be hosted on a remote site and linked.