Ripple counter, reset problem (J-K flip flop counter)
Replace two input NAND gate with four input NAND gate ,connect flip flop outputs Q0 and Q2 directly to it. Pass Q1 and Q3 through NOT gate and then connect the outptut to input of 4 input NAND gate. Apply the output of 4 input NAND gate to the clear of four flip flops.
See if it works.