Program optimization

I have quite a few places in my program where input from the user is required. I want the user to be able to press q at anytime, so that they go back to the beginning of the program (where there is a little menu, and the whole things starts again. You can see in the program where i have an if statement, trying to do this, but it is not a solution for any point in the program.

Any ideas?

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <Windows.h>

int main()
{
    char *options[100], *as[100], *bs[100], *cs[100], *Xos[100], *Yos[100], *Zos[100], *filename[20];//the s at the end of the name tell me it is stored as a string.
    float a, b, c, Xo, Yo, Zo;
    FILE *recentdata, *EulerData;//pointer to store recent data in text file.
while (1)
{
    menu();
    scanf("%99s", options);

    //What to do if user types exit
    if(strcmpi(options,"exit") == 0)//compare options to "recent" NOT case sensitive.
    {
        exit(0);

    }

    //What to do if user types q
    else if(strcmpi(options,"q") == 0)//compare options to "recent" NOT case sensitive.
    {
        system("cls");
        



    }

    //What to do if user types recent
    else if(strcmpi(options,"recent") == 0)//compare options to "recent" NOT case sensitive.
    {
        recentdata = fopen("recentdata.txt", "r");
         fscanf (recentdata, "%s %s %s %s %s %s", as, bs, cs, Xos, Yos, Zos);
         fclose;

    }

    //if the user didnt type recent, they typed something else in...?
else
{
    strcpy(as,options);//copy the value of options into as.
    scanf("%99s", bs);
    scanf("%99s", cs);
    printf ("%s %s %s\n\n", as, bs, cs);

    printf("Please input Xo, Yo and Zo\n");
    scanf("%99s", Xos);
    scanf("%99s", Yos);
    scanf("%99s", Zos);
    printf ("%s %s %s\n\n", Xos, Yos, Zos);

    recentdata = fopen("recentdata.txt", "w");
    fprintf(recentdata, "%s %s %s %s %s %s\n", as, bs, cs, Xos, Yos, Zos);
    fclose;

}

        a=atof(as); //converting strings to floats so that the compiler understands it is a number that can be used mathematically.
        b=atof(bs);
        c=atof(cs);
        Xo=atof(Xos);
        Yo=atof(Yos);
        Zo=atof(Zos);

        printf (" a = %.2f\n b = %.2f\n c = %.2f\nXo = %.2f\nYo = %.2f\nZo = %.2f\n", a, b, c, Xo, Yo, Zo);

        printf("Beginning execution of improved Euler...\n\n");
        Sleep(1000);
        printf("Please enter the name of the file to store the data in\n");
        printf("If it doesnt exist, it will be created.\n\n");
        scanf("%s", filename);
        printf("\nStoring all Data in file '%s.txt'\n", filename);
        Sleep(1000);


}
return 0;
}

int menu()
{

    printf("Type 'recent' to use the last entered data or:\nInput a, b and c, hitting Enter between each one,\n");
    printf("Typing 'q' at any time will bring you back here,\n");
    printf("To exit the program, from this screen type 'exit'.\n");

return(1);
}

char *options[100]

should be
char options[100]

for what you want to do is a little bit advanced to implement...

maybe it will be enough on any step where you ask some input from user check that it is 'q'?

also - you need to work on your indentation and maybe add more functions like menu() that do small tasks, instead of one long main that is hard to read