Have you restored the directory structure? I haven't really played around with the PSP's storage card much, but try restoring the following file tree (PSP being the root directory - don't create it).

PSP/game for PSP software (not save data)
PSP/music for music
PSP/photo for pictures
PSP/savedata for all of your save files

In your savedata folder, you should have a bunch of subfolders with names like ILJS00002 (it's the product code of the game). Inside each subfolder, you should have a couple of icons (icon1.png and icon2.pmf), a sound file (snd0.at3), a background picture (pic1.png) and game metadata (param.sfo).

If your existing savefolders don't have these icons and restoring the directory structure doesn't work, try wiping the card clean and making a new save for the games you need. Then check if the missing files are on your memory card and replace into the old folders as necessary.