Other suggestions going forward:
1. put system("cls") in its own function named something like clearScreen. That way it's not only self-documenting, but it allows you to change how you clear the screen in the future.
2. You mean "lose" not "loose". And "your" not "tour" Minor gripes, but it's always good to strive for polished language.
3. Speaking of self-documenting, some of your comments are too obvious. If you have a function named displayMenu then having a comment saying to display the menu to the user isn't too helpful. Since displayMenu only does one thing the function name provides enough information that having a comment is unnecessary.
4. Like you did with getting the menu selection, why not do the same with getting a guess?
5. This isn't very important right now either, but there's an issue with the distribution of your random number. Let's say for the sake of argument that rand gives you a number between 0 and 149. If that happens then your rand()%100 will mean numbers between 0 and 49 will occur twice as often as numbers between 50 and 99. In reality the probability of each number occurring for you will be more even than that, but it won't be as even as it could be. The generic code using rand() to generate an integer range between min and max is:
int(((double) rand() / (RAND_MAX+1)) * (max-min+1) + min)
What this does is convert the original rand() integer to a double, then scales the range from 0 to RAND_MAX to 0 and 1. RAND_MAX is a constant supplied by the compiler containing the largest random number it will give you. Next, this floating point range is scaled back up to an integer range with a spread between min and max, in your case you'll get numbers 0 thru 99, inclusive (inclusive meaning both 0 and 99 are included). Then the spread is offset by the minimum range you want, in this case 1, to get the range 1 to 100, inclusive.
So in your case it would be:
int randomNumber = int(((double) rand() / (RAND_MAX+1)) * (100) + 1);
Although you might want to make the generic version into a function for the sake of re-usability. Then you could call, for example, randomRange(1, 100) or randomRange(-10, 10). If you changed the variable types of min and max to be doubles instead of integers you could even do randomRange(0.1, 0.5).