Problem with SD card and with refreshing media

Lately I’ve tried to copy around 35 GB of music on a cheap 64 GB micro sd card, everytime it finished, it said there was 35 gb on the sd card, but when i viewed it, around 90% of the folders were empty. When I insert it in the sandisk sansa + it freezes on refreshing media and never ends. I have formatted the sd card as is stated in lots of topics, to FAT32. 

So basically I have 2 problems but maybe the whole problem lies in the sd card. Should I move to a more expensive one? Or can I fix these problems? I am really frustrated that I cant use my sandisk sansa clip +.

First off, are you sure that the card is a genuine card and really has 64GB of memory?  You might want to run it through simple testing, to make sure; freeware H2testw is well regarded for that.  Info.: