When I was drawing illustrations today I wanted to use a slightly different pen I found material and downloaded, I found that all the materials I had previously downloaded are lost, except for some.
Apparently, they existed in various tool columns and were able to be used normally.
"Various tools", "image material", "all materials" remain, but the file "download" of the material is still not displayed except for those downloaded today.
There is no particular problem in playing with graffiti, but tones and textures used by pulling from the material column have also disappeared from the file of "all materials", so I was in a situation where I could not use it so let me know Whats wrong?

I downloaded it and it is in exactly the same state as deleting it because it is no longer necessary, but at least I do not remember deleting it myself. (There is not enough time to erase all of them in the first place)

I did not use any of them at all, so I guess it's okay, but I do not mind feeling that Kakeami's tones and some textures were used quite often like every time.
Although it is also hand-re-downloading one by one, if you do it, it gradually downloaded from about two and a half years ago, so it's severely melancholic because it's in quantity.

Anyway, I want the things downloaded so far to come back.
What should I do?