I bought a second hand. I bought a second hand ps2 games console from a shop known as cash

Question

I bought a second hand ps2 games console from a shop known as cash generators. It was a while ago now. I later triedone of the view games that i have, shortly after realising that i didn`t buy a memory card at the time i bought the ps2. Anyway the on screen menu still asks for the memory card even though it was inserted into the slot. It doesn`t work in either. The memory card works in a friends ps2. I`ve looked about the internet for any possible clues but with no luck, I Couldn`t imagine the fault being dirty or worn contacts as again the memory card isn`t shown to be inserted in either slot in the ps2. you`re assistance would be of help and to ease my frustration. I couldn`t return the ps2 to the shop from where i bought it having mislaid the reciept!!!. Thank You in advancd