i went to design counter to count two numbers only (0 and 5) using flip-flop
yes i need to count two numbers only 0 and 5What exactly do you mean count only 0 and 5?
Do you want a circuit whose output will be the alternating sequence of 0 and 5?
If so, you can just make a counter that will count from 0 to 1. You can use any single Flip Flop do to that.
Then, take that as an input and form 4 different outputs that will produce either 0 or 5.
Is that clear?