sliding door lock

Hey Sanjeev. This thumb lever looks like our 82-107, which is used with these type of handle sets. Look it over and see if you agree. Note that this kind of damage is sometimes indicative of the door's internal mortise lock being broken. To test this, remove your handle set and try manually throwing the old lock with a flathead screwdriver. If it doesn't budge, then you know the mortise lock also needs to be replaced. 

I'm afraid I don't have a video that shows the aforementioned process, but what I mean is basically this: remove your handle set from the door, then take a flathead screwdriver. Insert that flathead into the 'keyway' that the tailpiece of the thumb lever usually goes into to interact with the mortise lock, then try seeing if you can use the screwdriver to get the lock to turn. If it doesn't budge, then the lock is broken. If it does move, then it's fine. 

Have you tried re-installing the handle set to see if that makes a difference? The video below shows how to re-install a very similar version of this handle set.

I do recognize this handle set, but I am afraid it's not a kind we can replace. I believe this is part of a multi-point lock system. Nothing we have will replace this, but a local hardware store may be able to assist you. If the lock is still caught to the door at all, you may need to contact a local pro for assistance; unfortunately, this can become a hassle. I apologize we can't be of more help, and best of luck with the repair. 

I don't have any specific contacts in your area I'm afraid, but you can see a list of handypersons and pros in the Burlington area here. And to answer your other question, no, I don't think our Legacy style handle sets are going to work with your door. The hardware is just too different. Apologies for any inconvenience.