Can't Reformat SD Card, Erasing Stuck at 'Unmounting'

Hi there, hoping to get some feedback. I am very not tech-savvy and am having a hard time understanding what has happened even after researching. I have an SD card that I wanted to empty. I connected it to my computer, copied the photos to an external, and deleted the photos on the card. Ejected card. Camera shows the card is still full. Connect SD card again, empty garbage bin. Go to Disk Utility. Try to erase, does not go past 'Unmounting'. Force quit. Connect SD card again. Now not readable. Back to Disk Utility. Failed repair. Tried to erase. Does not go past unmounting, though card info says it's already unmounted. There is an option to 'Mount'. Does nothing.

What is going on please? I just want to take photos and delete them.. is that not normal? Isn't this what you do with an SD card? Anyway, just frustrated. Help is very appreciated, thank you.