Paul has an LG G3, took his memory card out, put it on another phone, and now it won't mount. Leo says it's probably a format that isn't read because the other phone is older. Now he can't get the data because the older phone damaged the card. Leo says that he can get a program that can read it called Recuva which is free. That should be able to get the data off. PC Inspector will also do it.
The chatroom likes PhotoRec. The fact that Paul can see it and the phone wants to format it means there has to be data on it somewhere that he can recover. But don't pay for it.