I use to wear braces and I got them off about 10 years ago.I notice my teeth in the front have starting shifting.Will a retainer correct the problem without wearing braces again ?Teeth have shift slightly at bottom and top in the front of my mouth...

Retainer will not correct the current problem, it will have to be braces again. How old were you when you originally had the braces on, because braces are worn by adolescents whose teeth have not firmed up in the bone as yet, therefore the braces can correct the movement and keep them in place until everything is stabilized for adulthood.

You either took the brances off too soon or started them too late.

I'm guessing you no longer have your retainer from ten years ago. You can go to an orthodontist and see if a removable appliance could help. However, teeth do shift if you don't wear it. A new retainer would have to be shaped to apply force to move the teeth back, so you'll have to see what the orthodontist says. If you end up having some kind of appliance, when you're done, do wear the retainer - usually 24/7 for several months, then nights forever - it's really no big deal and it's worth it. Good luck.