Volatile vs. Interlocked vs. lock

Let's say that a class has a public int counter field that is accessed by multiple threads. This int is only incremented or decremented.

To increment this field, which approach should be used, and why?

• lock(this.locker) this.counter++;,
• Interlocked.Increment(ref this.counter);,
• Change the access modifier of counter to public volatile.

Now that I've discovered volatile, I've been removing many lock statements and the use of Interlocked. But is there a reason not to do this?