Gmod wont appear in taskbar but will appear in taskmanager. Won't Launch Properly. Can't get any help

Yesterday I ran Counterstrike Source and It ran fine. Then I closed it and ran Gmod. It ran fine too. I closed it because it with task manager was having trouble loading the map. I then went to start it again but it would only display the loading screen with the loading icon in the corner. So I again closed it using task manager again. Then I try to run it again but it only displays the launching window in steam. When the launching window closes I get the loading icon for the mouse for a second then nothing.

hl2.exe appears in taskmanager but It doesnt appear in a window.

I use windows 7 Home Premium Service Pack 1
I have 2G of RAM
Processor: Pentium® Dual-Core CPU T4500 @ 2.30GHz
I run a 64 bit operating system.
I have everything I need to run the game. Not that it is all listed above but if I didn’t it couldn’t have run before.

Things I have tried.

Running in 32 bit using steam
running in a windowed mode
running in the lowest resolution using steam launch config
checking for corrupted files
reinstalling steam
repairing steam
deleting clientregistry.blob
deleting appupdatestatus.blob
moving the garrysmod folder into the sourcemods folder

There so many things I’ve tried I can’t remember them all

I have bitdefender for sercurity but have allowed steam.exe, hl2.exe and gameoverlayui.exe through my firewall

I also have a problem where when I start downloading sometimes it goes to about 100kbps download speed and then just slows down untill it stopped downloading anything but still says downloading in the bottom of steam.

I’ve searched and searched for days now but nothing helps.

Counter Strike source wont run anymore either.

Please answer my question. My Dad and I are financially struggling so I don’t get to do much and we cant afford to upgrade my desktop which only has 256mb of ram.
Thank you in advance for any useful help.

[editline]2nd September 2011[/editline]

No one is replying. Is it too hard for anyone to answer?