Dell Windows 7 Computer- SD SLOT ISN'T WORKING RIGHT. Click.?

It has worked all the time until last night. I tried to put my SD card in, and nothing came up like it usually does. So I went to 'Computer' and it said it was there "Removable Disk (F:)". So when I double click it, it opens a window that says "Please insert a disk into Removable Disk (F:)" I have no clue what's going on! The SD card works fine. I even put a separate one in, and it said the same thing. :( Please help me.