Can I file a petition for my husband if he had a felony 6 years ago?

Your question requires an attorney consultation. It is not a simple question that can be answered on this type of forum. There are many factors that would need to be considered and evaluated. Drug possession can make your husband inadmissible and unable to obtain any immigration benefit, including becoming a permanent resident and citizen and can make him deportable. The fact that "the lawyer he had advise him to leave the country and not present himself to court" is troublesome to say the least. If this is true, you husband may be able to get the convictions set aside for ineffective assistance of counsel. I strongly suggest that you contact an experienced immigration and criminal defense attorney for a face-to-face consultation and give them all of the facts surrounding your husband's case. They would then be in a better position to analyze his case and advise you of his options. You should bring any documents you have pertaining to your husband's conviction for the attorneys to review. Good luck.