Cancelling 'Error Checking' to prevent data loss!

           While I started using an USB or an SD card inserted in my computer port, a box was displayed saying that there is a problem with it and to scan it; if I denied scanning to proceed on, there was another display in the screen to 'Repair this drive'! When I encountered this for the first time, I clicked on the 'Repair drive' fearing data loss. But actually I lost all the data after it from the SD card that I used! Next time, I met the same problem with an USB. I cancelled that display box titled as 'Error Checking' and saved the data loss from the USB. Do you have such an experience? Share it.