Need info, what kind of 3ds is this?
(2DS/3DS/3DSXL/N2DS/N3DS/N3DSXL?)
Do you use a SD card or a micro SD with SD adapter or plain micro SD?
What size, brand, formatting (Fat32, cluster ?)?
Problem: your 3ds does not see the sd card anymore, hence after boot all installed game icons are missing...