There is no logical errors with my code, but when I compile recover.c, a file called "recover" is produced, and when I give the command "./recover card.raw", it returns nothing to me (basically i only see "recover/ $" in my terminal).

Here is my code

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>

#define BLOCK 512
typedef uint8_t BYTE;



int main(int argc, char *argv[])
{
    //reject invalid input
    if (argc != 2)
    {
        printf("Usage: ./recover IMAGE");
        return 1;
    }
    // Open memory card and reject if invalid file
    FILE *file = fopen(argv[1], "r");
    if (!file)
    {
        printf("!file\n");
        return 2;
    }

    BYTE temp[512]; //allocate memory to a block (for reading)
    char filename[8]; //allocate memory to filename
    FILE *img; // there exists a file
    int count = 0; // increase counter to read subsequent blocks

    while (fread(temp, sizeof(BYTE), BLOCK , file) == 512)
    {
        BYTE buffer[4];
        fread(buffer, sizeof(BYTE), 3 , file); //fread returns the number of items of size "sizeof(BYTE)" that were read, which is "3")
        // look for beginning of a .jpeg (0xFF 0xD8 0xFF 0xe?)
        if (buffer[0] == 0xff && buffer[1] == 0xd8 && buffer[2] == 0xff && (buffer[3] & 0xf0) == 0xe0)
        {
            sprintf(filename, "%03i.jpg", count);//TODO: 2 is a constant. Change later to increments. Change filename as well to increment
            // open a new jpeg file, formatted as ###.jpg, starting at 000.jpg
            //if loop to close the previous file (if previous file exists)
            if (count > 1) //no need to close anything if first jpeg
            {
                fclose(img);
            }
            //This can be done by if counter = 0, continue searching for first jpeg, if counter != 0, close prev file and open new img
            img = fopen(filename, "w");
            if (!img)
            {
                printf("!img\n");
                return 3;
            }
            fwrite(temp, BLOCK, 1, img);
            count++;             // write 512 bytes into new img file
        }
        else if (count > 0) //
        {
            fwrite(temp, BLOCK, 1, img); //write 512 bytes as a continuation of current opened jpeg file
        }
    }
}

Thanks in advance for helping me!