Hi docs, would my retainer put my teeth back if I haven't worn them for a while?

Sort of. Retainers are not full control appliances like braces. When retainers not worn teeth shift, drift, tip, torque, rotate. Retainers retain, they don 't correct. If movement very slight, retainers may help. If more than slight, you will only get partial response to putting retainers back in. Best advice, get in to see your orthodontic specialist asap and be honest about your lack of compliance.