I own a hp laptop with specs-:
Amd a8 7th gen @2.37ghz
Radeon r5 m330 2gb vram
...i played watch dogs 2 ..n it was hella laggy ....black flag was laggy too...can i share my ram with vram to increase it??? Or do i have to upgrade ram first in order to do so?.. And would readyboost help anyway?
No, you wont be able to share your RAM with the VRAM. Your laptop is very low spec. 4gb of RAM is just enough for web browsing these days. At a minimum you would need 4gb more RAM and that would still not address the underpowered m330.
If it were me, I would not spend any money trying to upgrade that laptop. Rather save that money and put it towards a new laptop.
As Froggy said your laptop is very underpowered, 2gb of VRAM is very low, 4 or 8 is typical now days, also 4gb of RAM is cutting it really low, I would recommend at least 8gb or 16 for most gaming. Your best bet to play modern games is to buy a new system, or get used to playing older games. Hope this helped!