Why is data in my SD Card suddenly missing?

[Android Central Question]

I have little internal storage, so when my previous SD card looks like it's corrupted I think it's a good idea to have the next SD card as an internal storage. So I buy one and it's good so far. It turn out I forgot to move data from previous SD card so with hardship and other devices I succeed in moving it to my laptop because I don't have any card reader. Then I copy the data to the new SD card through my phone and it's good. Then I try to test how the data is read in the phone and while my picture reader can read them well, my music app (Musixmatch) can't read them at all. So i just restart the phone and hope for the best.

It turns out after I restart all data I have in SD Card just dissapeared. With it several apps that I have moved to SD card also vanished. I try to connect the phone to my laptop and it says correctly that my SD card have 22 GB in it but there is nothing there. I suspect my data just become hidden out of nowhere. It looks like my phone and my computer still detect that there is an SD card and that I have 22/59 GB in it but can't read any of the data. I have tried to see if the SD card is counterfeit so I install SD insight but it looks like the SD card is fine and have appropriate storage.

What should I do? I don't have card reader so is it really obligatory for me to buy it now? My phone is Lenovo Vibe K4 Note and my SD card is Vivan 64 GB and SD Insight said that the manufacturer is Jiaelec Corp.