By the time you left Qatar, it's either your sponsor has applied for cancellation of your visa or just waited for the expiry date. As far as I know, you are banned from entering Qatar for a period of 2 years. Since this period already lapsed, I supposed there should be no more problem. Anyway, your new sponsor will facilitate everything. Not unless you left Qatar before with unsettled loans, then dont dare come back otherwise the police authorities will put you in jail.