aggression

My four and a half month old puppy keeps showing its teeth when ever i try to put him on leash or try to lift him up.
Also when she doesn’t get what she wants, she keeps jumping up and snaps what ever she can reach, although she stops after a firm no, it is still a little scary.
How do I correct this?

What breed of dog is she? Is she your first puppy?

I agree with Sophie, a good puppy class can do wonders. In the meantime…
Keep the leash on her at all times when you can be watching her..let her drag it around or have her attached to your waist. (Do not leave her unsupervised, she can get caught and injure herself).
If she jumps and nips, tie her to a piece of furniture and leave the room. Wait. Return to her, if she jumps again, leave the room again. If she does not jump then give her a treat! GOOD DOG! and release her. Continue as necessary.

Take every opportunity to reinforce sitting as a default behaviour. Sit for food, sit for attention, sit before going for a walk etc etc. This way she learns good things come when she is calm. She is still a puppy and teething so make sure she has some good chew toys (with peanut butter or something in them) to keep her chewing on the appropriate things.

If you have a strong sit, the jumping can be stopped by asking for a sit instead (teaching an incompatible behaviour) and rewarding the sit EVERY TIME.

It is very important in teaching a pup it’s manners that you give it something to do INSTEAD of the bad behaviour…this gives the pup the option of two behaviours, one good (rewarded) and one not (ignored). The pup will learn to do the one that gets the reward. We spend a lot of time telling a dog what we DONT want but very rarely tell them what we DO want.

Don’t yell, don’t overcorrect, just ignore the bad and lead her to the good and make sure the rewards are good…dogs do what works for them….

I kind of figured by your screen name you were in india or somewhere in southeast asia. It certainly may be hard to find a trainer there.
Does she growl when she bares her teeth? Is it possible that she is doing a “submissive smile”? This looks like baring of teeth but is a wrinkled nose and only shows the front teeth..very common in the retrievers….
anyhoo..there are many really good training books available on the internet. If you can’t find a positive trainer, look for books on the net based on positive training (The Power of Positive Dog Training, by Pat Miller is a really good one) and start working with her at home…good luck!