SR flipflop problem

I think you are talking about the basic SR FF. This was done by connecting two nor gates in feedback (or two nand gates). So all you need is a combinatorial circuit:

q <= r nor qn;

qn <= s nor q;

s & r should be either 00,01,10 but not 11 hence the further development to D where S &R inputs were replaced by one input D that acts as S and internally inverted to act as R.

You may need to insert delays if your output vibrates.