Can't Run High Shadows in Source

[tweezy0914]

I've been playing GMod for about 2 years now, never knowing of the dynamic shadows of the Source Engine. But for some reason I cna't have the 'high' shadow setting?
I download ALL the proper and working drivers, but nothing happened except a FPS rise. I only ever can run up to medium shadows, and 'high' shader detail.

I posted this to technical support, still trying to get things to work even after the responses.
They said I should probably come here.

Anyone got any ideas on how to get them to work? (On a laptop, can't mod it, just the ram.)

Here are my stats for my computer:
Direct X 11
Acer Aspire 7750G-6645
Amd Radeon HD 7670M 1GB
3.1 GHz Intel i5-2450M
4 Ram
1600x900 Screen
It's made by Acer.(They never update drivers)

-Tweezy (YES, I'VE REBOOTED 2 TIMES)