I am having a problem with my gear selector.
In Park, the car doesnt move.
In Reverse, it does the same thing. It doesnt move at all when i press the accelerator.
In Neutral, the car moves forward
And Drive works normal.

I think that its a problem with the shift linkage but i dont know how to adjust it. Can any help me out?

 

Get the car up in the air and check out your linkage. It sounds like the actual transmission needs servicing, but double check your linkage first.