Ok So I bought coins that are now expired.
Does that mean that they cannot be traded and I have lost all the Bitcoin I invested in them?
I am not aware that any coin can expire. Coin may be dropped off o market but I think expiring is not the term. What coin specifically did you bought? A coin maybe dropped in an exchange but it may still be available in oter exhanges so you may want to check that first. You may still have a cjance to convert it back to bitcoin.