Simply put if your med is revoked or denied you can not fly sport pilot. If you simply let it lapse and not attempt to renew it, you can, by self certification and a valid drivers license. However since you have lost your drivers license you cant fly as a sport pilot even if you simply let your medical expire. I would contact the local chapter of EAA if you need any further qustions answered about the LSA rules. I hate to be the bearer of bad news but I think your unable to fly even LSA a this point. Good luck.