Default [Q] E: Can't mount /sdcard/ and no files found

Ive been having trouble and flashing roms for the past week trying to get my captivate to boot, but i constanly either get into a boot loop or i load into a black screen.

In CWM 5.1.0.7, when i choose "Install zip from sdcard > Choose zip from sdcard" i get a "E: Can't mount /sdcard/" error.

If i go to "Reformatting, tweaks and more > System Information > Browse directories and files", ill get "No files found." on a few of the directories and my /bin folder only has "init.goldfish.sh" in it. most of them have only bare minimal things in them. (im not sure if this is normal or not)

How should i go about fixing this?