Can't Put Anything on my R4?

It says that I only have 144 MB left but games like Bowsers Inside Story doesn't fit. Also I have 2 GB of space, and I'm using MAYBE 500 MB on the actual memory stick. Where did the other 1.5 GB of space go to?I took out Dragon Quest V ( which fitted before ) tried to put it in again and nope I can't, says there's no space. How does that make any sense?Help? What is going on? All I have is the Ys MENU stuff on my card and a GAMES folder with two sav files ( Pkn Plat and Suikoden Tierkreis ) Which is like 1 MB. So where did all my space go?Thanks.

Sometimes MicroSD cards can become corrupted.
You will need to backup any files you want to keep (like the Ysmenu stuff and save files) and then Format your card. You do this by right clicking on it and choosing "Format".Formatting will erase any files that are on the card permanently, so make sure you backup anything you want to keep.