Actually, prayer is extremely powerful and it can have all kinds of good effects. Some of them are not readily apparent or visible to us at the time.
Prayer suffers from the same problem that criminal lawyers do. If the lawyer’s client gets convicted, the client complains, “I hired you to get me off and you did a lousy job, here I am in prison! I’m not gonna pay you.” If the lawyer’s client is acquitted, the client says, “Well, the judge would have ruled that way anyway, even without a lawyer, because I didn’t do it and they had no evidence, so I’m not gonna pay you.” Similarly, when we pray and don’t get what we want, we think prayer is useless because it didn’t work, and when we pray and get what we want, we think prayer had nothing to do with it as God would have done the same thing without prayer.
It’s important to realize that praying for someone can have all kinds of good effects that are not limited to just good things happening for the person being prayed for. The prayers can have positive effects on the person doing the praying, on others in the circle of the pray-er and pray-ee, and even on the entire Church. Prayer is a mystery and it is very important. Do not underestimate it, even when the ill person doesn’t appear to be getting a physical cure.