The circuit that was linked to should work based on what you are asking.
This circuit uses a 555 timer configured as a re triggerable one shot. As long as a steady stream of pulses comes into the 555 the output on pin 3 remains high. However, if there is a break in the pulse train the 555 output will go low.
Missing pulse detectors look at the PRT (Pulse Repetition Time) or Frequency of an incoming pulse train. In the linked to circuit the values of R1 and C1 determine the RC time. As long as incoming pulses are within the RC time the 555 output remains high but if a pulse is missing it goes low.
Now if you want the circuit to latch when an incoming pulse train is missing a pulse then the 555 output could be used to trigger a D flip flop (or other flip flop circuit).
What exactly are you trying to do? You don't mention the PRT of the pulse train you want to monitor? Maybe with a better detailed explanation you could get better suggestions.
Ron