Windows Weird HL2 glitch need help.

Ok I'm at the end where all the strides keep coming out I got on top of the crumbling building and picked them all off then jumped down into this street square where I had to save barney and dog came running out. Now he is just standing there beating his chest in front of a combine wall and the entrance to the citadel I know there is an underground tunnel because I got annoyed after 30min of nothing happening so I used noclip and searched the map till I got the idea of going below the graphics and I saw the tunnel just under the wall where dog is standing, no matter what I do or what I shoot at it nothing happens barney just stands there and dog just beats on his chest. I don’t want to use no clip and just go into the tunnel and I've done everything short of restarting the level over.
Anyone else had this problem or know how to fix it?

 

.

 

No I have a full version bought at target for Christmas and I had to take my computer into work to get it installed because I have no Internet access at home.

 

.

 

I was afraid someone would tell me that, I had a hell of a time with those stupid striders. oh well if thats my only option then I guess thats what I'll have to do.
Thanks!

 

It's easier the second time though.

 

Sometimes loading your last save works. Ive had a few situations with Alyx not opening doors or whatever.

 

as above try reloading a save if you have 1 of before the dog and barney bit or even at the dog and barney bit, if you dont have 1 just cheat to get past it as that level is a biatch ,its a bit short n boring after that level tho