Default [Q] SD card issue

Sorry if this problem has been reported or discussed here before ... the search engine is down so couldn't search thru the forums for similar problems.

In a nutshell - SD card shows blank every time I swipe and activate my screen from inactive screen.

Details ...

I have a T-Mobile unrooted/unlocked GN2 and recently everytime I unlock my screen my SD card shows up blank. Unable to read any files/play music. I was using a 32gb sandisk hc microsd card. It worked on and off, randomly and finally stopped altogether saying damaged SD card. But when I plugged/mounted it in my pc I was able to recover the files without any issue. But regardless I purchased a brand new SD card 64gb this time and started using it, no problem up until after a week. So right after I hit the power button to screen lock and immediately after reactivating my phone and waking my screen ... it shows blank SD card and not reading it... please help