Search:

if ( noPrimesFound )
{
System.out.println( "No primes found in the specified range." );
}

At least you're honest. We're trying to give you basic debugging techniques that should help you find the source of the problem(s) and then fix them with or without our help. You can travel down...

Giving the user a blank screen and expecting him/her to know what to do with it is unfriendly and unreasonable. Improve your prompts so that the user knows what to do.

Adding prompts may also...